Fertilizering Containerized Plants IV

tapla (mid-MI z5b-6a)April 6, 2012

This topic has proven to be a fairly popular addition to the Container Gardening forum, having reached the maximum number of posts allowed on three previous occasions, so I'll post it for its fourth go-round. Nutrient supplementation has been discussed frequently, but usually in piecemeal fashion, on this forum and forums related. Prompted originally by a question about fertilizers in another thread, I decided to collect a few thoughts & present an overview that will hopefully be seen as a simplification and found to be helpful.

Fertilizing Containerized Plants IVcolor>size>

Let me begin with a brief and hopefully not too technical explanation of how plants absorb water from the soil and how they obtain the nutrients/solutes that are dissolved in that water. Most of us remember from our biology classes that cells have membranes that are semi-permeable. That is, they allow some things to pass through the walls, like water and select elements in ionic form dissolved in the water, while excluding other materials like large organic molecules. Osmosis is a natural phenomenon that is nature's attempt at creating a balance (isotonicity) in the concentration of solutes in water inside and outside of cells. Water and ionic solutes will pass in and out of cell walls until an equilibrium is reached and the level of solutes in the water surrounding the cell is the same as the level of solutes in the cell.

This process begins when the finest roots absorb water molecule by molecule at the cellular level from colloidal surfaces and water vapor in soil gasses, along with the nutrient load dissolved in that water, and distribute water and nutrients throughout the plant. I want to keep this simple, so I'll just say that the best water absorption occurs when the level of solutes in soil water is lowest, and in the presence of good amounts of oxygen (this is where I get to plug a well-aerated and free-draining soil). Deionized (distilled) water contains no solutes, and is easiest for plants to absorb. Of course, since distilled water contains no nutrients, using it alone practically guarantees deficiencies of multiple nutrients as the plant is shorted the building materials (nutrients) it needs to manufacture food, keep its systems orderly, and keep its metabolism running smoothly.

We already learned that if the dissolved solutes in soil water are low, the plant may be well-hydrated, but starving; however, if they are too high, the plant may have a large store of nutrients in the soil but because of osmotic interference the plant may be unable to absorb the water and could die of thirst in a sea of plenty. When this condition occurs, and is severe enough (high concentrations of solutes in soil water), it causes fertilizer burn (plasmolysis), a condition seen when plasma is torn from cell walls as the water inside the cell exits to maintain solute equilibrium with the water surrounding the cell.

Our job, because we cannot depend on an adequate supply of nutrients being supplied by the organic component of a container soil as it breaks down, is to provide a solution of dissolved nutrients in a concentration high enough that the supply remains in the adequate to luxury range, yet still low enough that it remains easy for the plant to take up enough water to be well-hydrated and free of drought stress. Electrical conductivity (EC) of, and the level of TDS (total dissolved solids) in the soil solution is a reliable way to judge the adequacy of solute concentrations and the plant's ability to take up water. There are meters that measure these concentrations, and for most plants the ideal range of conductivity is from 1.5 - 3.5 mS, with some, like tomatoes, being as high as 4.5 mS. This is more technical than I wanted to be, but I added it in case someone wanted to search 'mS' or 'TDS' or 'EC'. Most of us, including me, will have to be satisfied with simply guessing at concentrations, but understanding how plants take up water and fertilizer, as well as the effects of solute concentrations in soil water is an important piece of the fertilizing puzzle.

Now, some disconcerting news - you have listened to all this talk about nutrient concentrations, but what do we supply, when, and how do we supply them? We have to decide what nutrients are appropriate to add to our supplementation program, but how? Most of us are just hobby growers and cannot do tissue analysis to determine what is lacking. We CAN be observant tough, and learn the symptoms of various nutrient deficiencies - and we CAN make some surprising generalizations.

What if I said that the nutritional needs of all plants is basically the same and that one fertilizer could suit almost all the plants we grow in containers - that by increasing/decreasing the dosage as we water, we could even manipulate plants to bloom and fruit more abundantly? It's really quite logical, so please let me explain.

Tissue analysis of plants will nearly always show NPK %s to be very close to an average ratio of approximately 10:1.5:7. If we assign N the constant of 100, P and K will range from 13-19 and 45-70 respectively. (I'll try to remember to make a chart showing the relative ratios of all the other essential nutrients plants normally take from the soil at the end of what I write.) All we need to do is supply nutrients in approximately the same ratio as plants use them, and at concentrations sufficient to keep them in the adequate to luxury range at all times.

Remember that we can maximize water uptake by keeping the concentrations of solutes low, so a continual supply of a weak solution is best. Nutrients don't often just suddenly appear in large quantities in nature, so the low and continual dose method most closely mimics the nutritional supply Mother Nature offers. If you decide to adopt a "fertilize every time you water" approach, most liquid fertilizers can be applied at 3/4 to 1 tsp per gallon for best results. If you decide that is too much work, try halving the dose recommended & cutting the interval in half. You can work out the math for granular soluble fertilizers and apply at a similar rate.

The system is rather self regulating if fertilizer is applied in low concentrations each time you water, even with houseplants in winter. As the plant's growth slows, so does its need for both water and nutrients. Larger plants and plants that are growing robustly will need more water and nutrients, so linking nutrient supply to the water supply is a win/win situation all around.

Another advantage to supplying a continual low concentration of fertilizer is, it eliminates the tendency of plants to show symptoms of nutrient deficiencies after they have received high doses of fertilizer and then been allowed to return to a more favorable level of soil solute concentrations. Even at perfectly acceptable concentrations of nutrients in the soil, plants previously exposed to high concentrations of nutrients readily display deficiency symptoms, even at normal nutrient loads.

You will still need to guard against watering in sips, and that habit's accompanying tendency to ensure solute (salt) accumulation in soils. Remember that as salts accumulate, both water and nutrient uptake is made more difficult and finally impaired or made impossible in severe cases. Your soils should always allow you to water so that at least 10-15% of the total volume of water applied passes through the soil and out the drain hole to be discarded. This flushes the soil and carries accumulating solutes out the drain hole.

I use a liquid fertilizer with a full compliment of nutrients and micronutrients in a 3:1:2 ratio. Note that 'RATIO' is different than NPK %s. Also note how closely the 3:1:2 ratio fits the average ratio of NPK content in plant tissues, noted above (10:1.5:7). If the P looks a little high at 4, consider that in container soils, P begins to be more tightly held as pH goes from 6.5 to below 6.0, which is on the high side of most container soil's pH, so the manufacturer probably gave this some careful consideration. Also, P and K percentages shown on fertilizer packages are not the actual amount of P or K in the blend. The percentage of P on the package is the percentage of P2O5 (phosphorous pentoxide) and you need to multiply the percentage shown by .43 to get the actual amount of P in the fertilizer. Similarly, the K level percentage shown is actually the level of K2O ( potassium oxide) and must be multiplied by .83 to arrive at the actual amount of K supplied.

To answer the inevitable questions about specialty fertilizers and "special" plant nutritional requirements, let me repeat that plants need nutrients in roughly the same ratio. 'RATIO' is also an entirely a separate consideration from dosage. You'll need to adjust the dosage to fit the plant and perhaps strike a happy medium in containers that have a diversity of material.

If nutrient availability is unbalanced - if plants are getting more than they need of certain nutrients, but less than they need of others, the nutrient they need the most will be the one that limits growth. There are 6 factors that affect plant growth, vitality and yield; they are: air, water, light, temperature, soil or media and nutrients. Liebig's Law of Limiting Factors states the most deficient factor limits plant growth, and increasing the supply of non-limiting factors will not increase plant growth. Only by increasing most deficient nutrient will the plant growth increase. There is also an optimum combination/ratio of nutrients, and increasing them, individually or in various combinations can lead to toxicities and be as limiting as deficiencies.

When individual nutrients are available in excess, it not only unnecessarily contributes to the total volume of solutes in the soil solution, which makes it more difficult for the plant to absorb water and nutrients, it can also create an antagonistic deficiency of other nutrients as toxicity levels block a plant's ability to take them up. E.g., too much Fe (iron) can cause a Mn (manganese) deficiency, with the converse also true, Too much Ca (calcium) can cause a Mg (magnesium) deficiency. Too much P (phosphorous) can cause an insoluble precipitate with Fe and make Fe unavailable. It also interferes with the uptake of several other micro-nutrients. You can see why it is advantageous to supply nutrients in as close to the same ratio in which plants use them and at levels not so high that they interfere with water uptake. I know I'm repeating myself here, but this is an important point.

What about the high-P "Bloom Booster" fertilizers you might ask? To induce more prolific flowering, a reduced N supply will have more and better effect than the high P bloom formulas. When N is reduced, it slows vegetative growth without reducing photosynthesis. Since vegetative growth is limited by a lack of N, and the photosynthetic machinery continues to turn out food, it leaves an expendable surplus for the plant to spend on flowers and fruit. Plants use about 6 times more N than P, so fertilizers that supply more P than N are wasteful and more likely to inhibit blooms (remember that too much P inhibits uptake of Fe and many micro-nutrients - it raises pH unnecessarily as well, which could also be problematic). Popular "bloom-booster" fertilizers like 10-52-10 actually supply about 32x more P than your plant could ever use (in relationship to how much N it uses) and has the potential to wreak all kinds of havoc with your plants.

In a recent conversation with the CEO of Dyna-Gro, he confirmed my long held belief that circumstances would have to be very highly unusual for it to be ever beneficial to use a fertilizer in containers that supplies as much or more P than either N or K. This means that even commonly found 1:1:1 ratios like 20-20-20 or 14-14-14 supply more P than is necessary for best results.

The fact that different species of plants grow in different types of soil where they are naturally found, does not mean that one needs more of a certain nutrient than the other. It just means that the plants have developed strategies to adapt to certain conditions, like excesses and deficiencies of particular nutrients.

Plants that "love" acid soils, e.g., have simply developed strategies to cope with those soils. Their calcium needs are still the same as any other plant and no different from the nutrient requirements of plants that thrive in alkaline soils. The problem for acid-loving plants is that they are unable to adequately limit their calcium uptake, and will absorb too much of it when available, resulting in cellular pH-values that are too high. Some acid-loving plants also have difficulties absorbing Fe, Mn, Cu, or Zn, which is more tightly held in alkaline soils, another reason why they thrive in low pH (acid) soils.

So, If you select a fertilizer that is close in ratio to the concentration of major elements in plant tissues, you are going to be in good shape. Whether the fertilizer is furnished in chemical or organic form matters not a whit to the plant. Ions are ions, but there is one major consideration. Chemical fertilizers are available for immediate uptake while organic fertilizers must be acted on by passing through the gut of micro-organisms to break them down into usable elemental form. Since microorganism populations are affected by cultural conditions like moisture/air levels in the soil, soil pH, fertility levels, temperature, etc., they tend to follow a boom/bust cycle that has an impact on the reliability and timing of delivery of nutrients supplied in organic form, in container culture. Nutrients locked in hydrocarbon chains cannot be relied upon to be available when the plant needs them. This is a particular issue with the immobile nutrients that must be present in the nutrient stream at all times for the plant to grow normally.

What is my approach? I have been very happy with Foliage-Pro 9-3-6 liquid fertilizer. It has all the essential elements in a favorable ratio, and even includes Ca and Mg, which is unusual in soluble fertilizers. Miracle-Gro granular all-purpose fertilizer in 24-8-16 or liquid 12-4-8 are both close seconds and completely soluble, though they do lack Ca and Mg, which you can supply by incorporating lime or by including gypsum and Epsom salts in your fertilizer supplementation program. Ask if you need clarification on this point.

I often incorporate a granular micro-nutrient supplement in my soils when I make them (Micromax) or use a soluble micro-nutrient blend (STEM). I would encourage you to make sure your plants are getting all the micro-nutrients. More readily available than the supplements I use is Earth Juice's 'Microblast'.

When plants are growing robustly, I try to fertilize my plants weakly (pun intended) with a half recommended dose of the concentrate at half the suggested intervals. When plants are growing slowly, I still fertilize often, but with considerably reduced doses. It is important to realize your soil must drain freely and you must water so a fair amount of water drains from your container each time you water to fertilize this way. Last year, my display containers performed better than they ever have in years past & they were still all looking amazingly attractive at the beginning of Oct when I finally decided to dismantle them because of imminent cold weather. I attribute results primarily to a good soil and a healthy nutrient supplementation program.

What would I recommend to someone who asked what to use as an all-purpose fertilizer for nearly all their container plantings? If you can find it, a 3:1:2 ratio soluble liquid fertilizer (24-8-16, 12-4-8, 9-3-6 are all 3:1:2 ratio fertilizers) that contains all the minor elements would great.

How plants use nutrients - the chart I promised:

I gave Nitrogen, because it is the largest nutrient component, the value of 100. Other nutrients are listed as a weight percentage of N.

N 100

P 13-19 (16) 1/6

K 45-80 (62) 3/5

S 6-9 (8) 1/12

Mg 5-15 (10) 1/10

Ca 5-15 (10) 1/10

Fe 0.7

Mn 0.4

B(oron) 0.2

Zn 0.06

Cu 0.03

Cl 0.03

M(olybden) 0.003

To read the chart: P - plants use 13-19 parts of P or an average of about 16 parts for every 100 parts of N, or 6 times more N than P. Plants use about 45-80 parts of K or an average of about 62 parts for every 100 parts of N, or about 3/5 as much K as N, and so on.

If you're still with me - thanks for reading. It makes me feel like the effort was worth it. Let me know what you think - please.

Here is a link to the previous posting of A Fertilizer Program for Containerized Plants, in case you'd like to review some of the exchanges.

Another thread that has proven very helpful to a goodly number of forum participants can be found by following this link to information about How Water Behaves in Container Media. You'll find it a fairly detailed discussion about container soils.

Take care. Good luck and good growing!


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Congrats on turning this thread again! I hadn't read it before, did so and then all the exchanges. My eyes are kinda bleary but it's great stuff, and I learned so much! Now I have to research and learn about "Pro-Tekt", that's new to me. The learning never ends, and thank heavens for it!
Al, thanks so much for all you do....

    Bookmark   April 6, 2012 at 9:43PM
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tapla (mid-MI z5b-6a)

.... and thank YOU for your kindness, Mary. I long ago discovered I enjoy being around plant people and enjoy sharing what I can with them. It just seems like a natural extension of the enjoyment I get from nurturing plants. So glad you're joining us!


    Bookmark   April 7, 2012 at 9:08AM
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I feel like I have learned so much from tapla I have to show it in this thanks. Thanks again.

    Bookmark   April 7, 2012 at 11:23AM
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Hi all. First off, I'd like to thank Al for all the information he has and continues to share with all of us! Thanks, Al!

I am gearing up to try the 5:1:1 mix this year and thought it'd be a good idea to read up on fertilizing as part of the process. :-) I have a couple of questions.

1. With houseplants, how does everyone water until it runs out more than just the little trays? It seems like a lot of work to take the plants outside or to the sink/tub every time you water. Particularly if they're larger plants. I was planning on fertilizing with every watering at 1/4 strength. But, this has me concerned that maybe I should look at a different regiment if I don't want to haul them back and forth.

2. For my (upcoming) outside containers, I was thinking of mixing in some CRF to get through the usually very wet Spring, then when the rain tapers off (or as needed) using Foliage Pro 9-3-6. But, in reading through the thread, it seems that most don't use CRF. Am I better off just skipping it, and if it rains too much, they don't get fed? Or perhaps, go ahead and feed/water even if it's raining?

Thanks for your thoughts!

    Bookmark   April 15, 2012 at 7:24PM
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similar questin to tsheets. If mixing in osmocote CFR in 5-1-1 for berries (straw, rasp, black), when should i start fertilizing? rasps and blacks are just starting to grow. Strabs have 2-5 leaves each and i have been pulling off flowers already. Also, i am using granular miracle grow, how much epsom salt do i need to mix in? (2 gallon watering can).

    Bookmark   April 16, 2012 at 10:07AM
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tapla (mid-MI z5b-6a)

TS - For over-wintering plants, I fertilize with each watering. I direct water in a narrow stream so it covers the entire soil surface. When water starts to appear in the collection saucer, I stop watering. Usually, about 15-20% of the water I applied collects in the saucer & evaporates before the next fertigation. All I need to keep track of is what day it is, so I know when it's time to water - which is kind of nice.

Alternately, you could fertigate-flush-flush on a weekly or bi-weekly basis, or even water in sips & flush the containers thoroughly on a monthly basis.

Most people think that because a fertilizer might be soluble, that it gets flushed from the soil very quickly. Container media does retain some level of nutrients against rain in plenitude. Usually, it's only a day or two after it stops raining that you'll need to water again anyway, so I've never looked at it as that big of a deal - but there's no harm in using CRFs, other than you lose the ability to withhold fertilizer in the really hot periods.

Q - it's not clear what soil you're using, so I don't know if the Epsom salts is appropriate. You can incorporate CRFs into the soil when you establish your planting, but it's best not to incorporate if you intend to let the soil sit for an extended period or you could experience fertilizer burn.


    Bookmark   April 16, 2012 at 3:03PM
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I mixed up some of your stuff, the infamous 5-1-1 (after having many many questions answered by you and the fine folks here). I mixed in osmocote when i planted approx 3- 4 weeks ago. I am not sure what you mean by let the soil sit for an extended period of time? I only mixed up what i needed plus one small extra batch without CRF in it. I have been watering heavily when they have needed water until significantly running out the bottom.

    Bookmark   April 16, 2012 at 6:03PM
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Thank you, Al. That helps! I am just afraid there won't be a significant amount of run off before the saucer is full. Maybe what I'm envisioning as 15% - 20% is more than what it really is. But, if flushing once a month would be sufficient, I can live with that. I wouldn't say I water in sips, but, I usually end up learning the hard way how much water it takes before it starts to run out and stop at that point.

As far as the CRF, I guess I didn't really know what to expect in watering frequency. I've never used anything like the 5:1:1 before, so, learning as I go. :-) With the peat based commercial mixes I've used, I rarely have to water before mid - late June. :-)

Thanks, again!

    Bookmark   April 16, 2012 at 8:48PM
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tapla (mid-MI z5b-6a)

Q - If you make a batch of soil and incorporate the CRF into it, it's going to continue to release fertilizer as long as it's moist and temps are close to the 65-75* range, lower temperatures retarding release & higher temps accelerating it. So, for example, if you make a soil in the spring with CRF included & don't use it until fall or the following spring, you could easily burn plants when you plant in it. That's why it's best to wait until you're ready to plant before you add the CRF.

Best luck to you guys! I'll be waiting on your results.


    Bookmark   April 17, 2012 at 2:56PM
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Thanks Al. What about the fertilizing question? How much miracle grow granular (i would prefer applying no more than 1x per week), epsom salt, etc? for a 2 gallon watering can? Also, anyting what else if anything do i need to add? I did not incorporate lime into the 5-1-1. I remember PJ using vinegar for his strawbs, is it necessary? would it help the other berries too?

    Bookmark   April 17, 2012 at 4:35PM
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tapla (mid-MI z5b-6a)

Will you be using anything else, or is there already a nutrient source (CRF) in the soil? Why no lime? What are you doing to ensure a Ca/Mg supply?


    Bookmark   April 19, 2012 at 2:08PM
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I didn't add lime upon your suggestion that the brambles would prefer a more acidic growing medium (I forgot that i may need to add that to the strawberries). I added osmocote CRF when i made the soil (a week or so in advance of planting).

As far as "What are you doing to ensure a Ca/Mg supply?", I am posting and asking your advice as to what i need to do :). I would prefer to use up the granular MG fertilizer that i have had for a long time. I will just buy the Foliar pro (I think that is the one you recommend) with micronutrients if that will be significantly easier.

I truly appreciate all the help you provide. I am even passing along this obsession, as my 3 year old constantly asks if we can go check on "our" plants when i get home from work.

    Bookmark   April 19, 2012 at 6:38PM
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tapla (mid-MI z5b-6a)

Hmmmm - I don't think I would have said that (not to add lime to the 5:1:1 mix - any chance you misunderstood or said you were using the gritty mix - or we got our soils mixed up? Even if I knew you were using FP, which has Ca & Mg, I still would have suggested you lime the 5:1:1 mix. How far along are your plants? Are they well-rooted yet?


    Bookmark   April 19, 2012 at 9:47PM
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I appreciate the diplomacy, but my money would be on me having misinterpreted something. Strawberries in flower boxes are flowering. Rasp and blacks are all leafing out (except one). Can i amend the top few inches of soil with lime? How much lime for 20" pots. What else do i need to add to the MG when fertilizing? I am planning on weekly at about 1/4 strength or so (or less if you tell me otherwise).

For fertilizing cherry trees in Gritty mix. I was planning to mix in the same CRF and use the same MG. Also, i don't know that i can find gypsum to mix in, should i mix in epsom salts? I though i had this all straight after reading everything a few months ago but it seems like in the excitement to get everything planted, i screwed up.

I have 2 cherry trees sitting in my garage waiting to be planted and enough gritty ingredients for one of them. The other may need to go into 5-1-1 for two years or so then into gritty later on (or maybe next spring).

    Bookmark   April 20, 2012 at 10:11AM
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tapla (mid-MI z5b-6a)

Estimate the volume of the container and then add in a teaspoon per gallon of soil and mix it into the top few inches of the soil if you can. I'd repeat that in about 2 weeks. Usually, you'd mix 2 -3 tsp/gallon of soil, but since you're just scratching it into the top layer of soil where all the roots are, I think it's a good idea to use some restraint, because it will contribute to the level of solutes in the soil. Once the lime is in the soil, you should be good for the entire growing season with just the MG. If you happen to go into next growing season with the plants in the same soil, you'll probably need to add an occasional bit of Epsom salts to your fertigation solution for the Mg; this, because the Mg fraction of the lime is about 125X more soluble than the Ca fraction.

For the cherry in gritty mix - incorporate 2 teaspoons gypsum (easy to find at this time of year - comes in 50 lb bags or 10 lb bags wherever Espoma products are sold) per gallon of soil. Also add (dissolve) 1/4 tsp Epsom salts/gallon of fertigation solution if you're fertilizing weekly, and 1/2 tsp if you're fertilizing less frequently.


    Bookmark   April 20, 2012 at 5:51PM
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Ohiofem(6a Ohio)

Hi, Al: I am interested in hearing your thoughts about fertilizing seedlings, specifically vegetable seedlings growing under lights in a soiless medium with no added nutrients with plans to transfer them to outdoor containers or raised beds at six to eight weeks. I have tomatoes, peppers, eggplants and okra that are three to five weeks old now. I started them in a standard seed starting mix and will soon repot into 5-1-1 with lime but no fertilizer. In the past, I would give them a little fish emulsion at half strength once a week after transplanting. Now I am wondering if I should use a chemical fertilizer like Foliage Pro instead since I believe you have said organic fertilizers depend on soil organisms to break them down into useable nutrients and those organisms aren't reliable allies in a container. Many years ago I burned my seedlings by feeding them Miracle Gro even though I thought I had dilluted to half strength. I have seen that many experienced growers don't fertilize their seedlings at all, but use a commercial potting mix with a light fertilizer charge, like Promix, instead. What do you do?

    Bookmark   April 22, 2012 at 10:19AM
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tapla (mid-MI z5b-6a)

I fertilize as the first true leaves start to appear. There is nothing credible to support the idea that the roots of seedlings are any more delicate than the newly forming roots of a 500 year old oak tree. The roots that do all the work on old oaks and acorn sprouts are the same age - yes? Aren't all the very fine feeder roots, the work horses, the youngest roots on ANY plant?

The fact is, the plants you describe need fertilizer or a ready source of nutrients. We can't expect the soil to provide a complete range of nutrients, let alone an adequate measure of everything commonly taken from the soil, so NOT fertilizing assures deficiencies - not the way you;'d like your seedlings to start their life, I'm guessing. I've seen the roots of small plants wrapped around granules of CRFs and slow release products as well.

...... another myth dispelled.

BTW - you can burn seedlings just as easily by over-applying an organic source of nutrients as by over-applying synthetic sources. Ultimately, it's the TDS that's going to determine what happens insofar as fertilizer burn goes. It's possible, that if the soil was cool, what you attributed to fertilizer burn was actually ammonium toxicity; a malady that doesn't get ENOUGH blame when soils are cool and urea or organic sources of N are employed because in almost all cases, it goes undiagnosed because we aren't able to make the connection.


    Bookmark   April 22, 2012 at 11:32AM
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Ohiofem(6a Ohio)

Could you say a little more about ammonium toxicity? Or more generally, different forms of nitrogen in synthetic fertilizers? I use FP on my houseplants and vegetables and (cheaper) MiracleGro 24-8-16 on my flowering annuals in containers. I notice the nitrogen in FP is mostly nitrate while the nitrogen in MG is mostly urea. Both contain a small amount of ammoniacal nitrogen. I was taught that some plants, like orchids, should not be fertilized with ammonia or urea, so I got the impression nitrate was the better form of nitrogen in general. But, I also have seen posters on this forum say that different forms of nitrogen are needed under different growing conditions or in different stages of life.

    Bookmark   April 22, 2012 at 12:39PM
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I never logged back on to say thanks. I added the lime (although i think i messed up the teaspoons to cups conversion and added about 25% too much).

Plants seem to be doing great except two flowerboxes of strawberries. the rest are growing great and these two seem stunted. I will post up some pictures in a separate thread.

    Bookmark   May 2, 2012 at 11:17AM
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Thanks so much for this Tapla.

How come those that understand science always agree that synthetics are best for container culture and understand plants can't tell the difference? Then you get these gardeners that want to look down on those that use synthetics and they do not even understand science?

I am so glad to find this sight, I have learned so much from Tapla.

    Bookmark   July 17, 2012 at 11:41AM
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Here's a question for Al. I have around 30 avocados started in containers. They are all in the "gritty mix" and doing well, about half of them have been moved outside, with the others waiting until they leaf out.

I've started brewing compost tea. I use a bubbler, so I'm going for max aerobic bacteria, mainly for use on my veggies, asparagus, grapes, and lawn. I'm adding molasses (powder) as well as vinegar to the brew, as per the guidelines found in the compost forum.

Is it a good idea to used it on my container avocados? If so, diluted of full strength?


    Bookmark   July 24, 2012 at 3:02PM
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I may save Al some words here. Gritty mix isn't suitable for organic growing as it's either non-organic media such as granite or turface, or a slow breaking down medium such as bark. You won't be able to maintain a microbial ecosystem in it. Best to save that mix for the ground.

    Bookmark   July 24, 2012 at 3:59PM
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High porosity grow media and organics do not mix.

    Bookmark   July 24, 2012 at 6:04PM
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OK, Thanks.

    Bookmark   July 24, 2012 at 10:07PM
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Hi All,

I'm new here. I 'stumbled' across the threads on Al's 5-1-1 Mix and Gritty Mix. I read all I could for about a week. I was so excited to get started and to have received a (possible) answer to my problem of my potting mix taking more than a week to dry out and some of my very young plants starting to drop leaves. I just made my 5-1-1 mix today.

5 parts pine bark (mulch)
1 part perlite
1 part miracle grow potting mix

I did not add dolomite at the time b/c I didn't have any at the time I did this. I have since gone out and bought some garden lime(derived from dolomite). It is Espoma brand (I think and it says it's "organic").

My question is:
Can I add a little dolomite to each small pot in the first layer or so of the soil? I do have Miracle Gro liquid fert. in the yellow bottle. It is the 3:1:2 ratio although I forget the exact numbers right now. I plan on fertilizing with that.

My second question is to Al(specifically):
First off, THANK YOU for all that you have shared and continue to share and the help you give and the support you supply to those of us who 'have ears to hear' and want to 'hear' more. Can you explain (again) and step by step for me on exactly how to water my plants? Do I need to water until the water begins to run out and then water again? or water until the water begins to run out of the bottom of the plant and then stop and drain and that's it?

Thanks once again!


    Bookmark   July 27, 2012 at 7:02PM
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aharriedmom(8B FL Sunset 28)

^ I'll be very presumptuous and add to her question. I have been watering several of my plants by sticking them under not-cold water from my kitchen sink. This, obviously, gets water on the foliage of some of them. So...

1) Do I need to be very careful about not getting fertilizer on the foliage when I water with the FP 9-3-6?

2) If so, what's the easiest way to water heavily foliaged or trailing plants with a watering can to fully saturate the entire surface of the mix but not get it on the foliage?


    Bookmark   July 31, 2012 at 7:33AM
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tapla (mid-MI z5b-6a)

Dee - your fertilizer is 12-4-8. Yes, you can add a little dolomite scratched into the surface soil.

If you have time (I don't), the best way to water is:
In the first pass, apply enough water to soak the soil, but not enough that any significant volume of water exits the drain. A few minutes later, make another pass, watering again so that at least 10-20% of the total volume of water applied in both applications exits the drain. The effluent should be separated from the soil entirely so there is no possibility the salts you flushed from the soil can find their way back into the soil. Never leave the pot sitting in the effluent.

I really like the 'those with ears to hear' phrasing. It's remarkable how many have their ears closed half the time. ;-)

HM - Foliar feeding is used mainly in agricultural applications when the plant is growing so fast it can't keep up with its own nutritional needs. Usually, it is limited to one of only a few elements. Roots are by far the most efficient pathway into the plant, so much so that you could say that if your containerized plants respond favorably to foliar feeding, there was probably something wrong with your nutritional supplementation program. I know that's not the question you asked, so count it a freebie. ;-)

How important not getting fertigation solution on foliage is will vary by species and the strength of the solution. The stronger the solution, the more likely it will be to blemish foliage. Also, certain plants (those with pubescent foliage, e.g.) are prone to being easily damaged by fertigation solutions. As a general practice, I try hard to avoid it entirely.

I use a water brake made by Masakuni to water. I use it in combination with a brass fitting on the hose end that shuts water on and off with a little lever. I sort of stick it into the plant where there is no foliage and water just the soil, trying not to splash any soil onto the lower foliage.


    Bookmark   July 31, 2012 at 8:00AM
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aharriedmom(8B FL Sunset 28)

What about indoor plants? ::

I have to admit that I've been (through total ignorance) a fertilizing-dummy. Outdoor plants have gotten time release capsules, at least in the spring.
But honestly, I'm ashamed to say, the indoor plant I've had the longest, the peace lily, hadn't been fertilized at all and I think I got it in 2009. A few months ago, before I read enough about plants, I divided and repotted it in MG soil. It took about 6-8 weeks before it decided it was going to stand back up and look alive. --You may recall that I emailed you and said I was terribly worried about it. It happened to start looking alive a day or two after my email so transplanting it into the gritty hasn't been as big a priority... which is good because it took me forever to get the ingredients and I still haven't found a bark that doesn't require a ton of sifting with great amounts of "waste." Of course, I will use the waste as mulch outside and the bark was just a couple of dollars, so excluding the time needed to get what I need, and the lack of time to finish the half-bag of unsifted mulch, it's not bad.

My recent purchase of the FP is my first houseplant fertilizer - up until the last couple weeks, everything was new in MG soil with added fertilizer so fertilization hadn't yet become an issue. Now that it is an issue, I realize how much more I have to learn.

BTW: when I transplant to gritty from an MG soil, do I fertilize with the initial, first watering or wait for the second watering?

I so appreciate your knowledge and willingness to share and educate! You have no idea how much.

    Bookmark   July 31, 2012 at 8:21AM
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aharriedmom(8B FL Sunset 28)

And a picture to add to my question:

It was very etiolated, so I cut the top off to root and the one leaf broke off --- but if it were a full rosette I'd have a difficult time wetting the entire surface of the soil without getting the bottom leaves wet.

Is there a trick to it, or do I just need to be super careful? I have a watering can with a narrow spout.

    Bookmark   July 31, 2012 at 9:04AM
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HM, I think that watering can with a narrow spout is your answer if you worry about getting leaves wet, unless you have too many plants to water...I use a spray, one of those plastic bottles with adjustable nozzle, you can really aim well with it.

    Bookmark   July 31, 2012 at 2:21PM
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tapla (mid-MI z5b-6a)

HM - first, if you have FP fertilizer, the learning curve isn't that steep. All you need to do is use it, and water in such a way that you ensure you won't have to deal with a salt build-up. Pretty easy, hmm? ;-)

Of course, that's the 'by rote' method. I'm hoping you take the time to become familiar with all the reasoning that went into fertilizer manufacturers developing their 3:1:2 ratio fertilizers, and why they work so well; but if you don't, it's not the end of the world. There's always tomorrow if the mood strikes you.

Thank you for the kind words. Whenever anyone makes an effort to help, it's always uplifting to know the effort is appreciated.

The plant in the picture should soon start backbudding from around the wound where you truncated the stem. A tip - use a fine twig or toothpick to paint the fresh wound with waterproof wood glue. Cover only to the very edge of the wound, but make sure you cover all exposed cambial tissue. This stops drying of the cambium and keeps it from dying back so far from the wound site.

This is a loose nozzle from a tube of caulking. I heated it and bent it, then threaded it over the spout of my 2L watering can.

It gets me in and out of tight places with ease. If you don't have a lot of plants, you might consider Rina's idea or a contact lens bottle that jets water out in a small, directable stream when you squeeze it. At work, I use a 24 oz condiment (squeeze) bottle I bought at GFS, a food store that caters to those who buy in large portions (restaurants, institutions, parties, large families ....)

Enjoy the day, guys!


    Bookmark   July 31, 2012 at 4:44PM
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Al, thanks for your response. I am slowly transitioning all my currently established plants over to the 5-1-1 mix. I am amazed and sometimes heartbroken over how compacted that MG potting mix had become(with plenty of watering over time-not overwater but enough water) in the bottom of these pots as I turn each plant out and 'dust' them off. I had no idea all that was going on inside. Some of these roots looked like they did not even penetrate through the mix to grow so they stayed in their original root ball...compacted and suffocating...no wonder my plants looked like they were not growing!! I'm soooo glad I found the information you gave on your 2 mixes. I love making my mixes up and tailoring them to each plant and experimenting with this whole process and tending to my plants.

I must say though that I am surprised that I'm not having to water as much as I thought. I made some batches of the mix with potting soil(for my plants that like it moist most of the time) and another batch without the potting mix. My bark seems to be mostly finely chopped/ground so I figured that would hold enough moisture without the potting mix for some other plants. I check everyday though for wetness/dryness...sometimes several times during the day, just so I can get a handle on how my plants behave in their individual mix. Thanks once again!

Harriedmom, I'm learning right along with you!!

    Bookmark   July 31, 2012 at 4:48PM
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tapla (mid-MI z5b-6a)

Oh, you're very welcome. I don't know what I did to wind up so blessed with the good luck of running into so many positive, open-minded, and enthusiastic growers the last week or few, but it's very refreshing.

I'd say that because of the superior aeration of both the gritty and 5:1:1 mixes, it's more than fair to say you'll need to water more frequently than when using nearly any of the more popular commercially prepared soils that have as their base a high % of fine particles - peat, compost, composted forest products .... For some reason, there is a small but vocal group of growers who wouldn't give any recognition to the attributes of any fast draining, well-aerated soils, much less one of the two I mentioned. I know I mentioned this recently - I just hope it wasn't on this thread so I come off as more redundant than I already am at times, but the few who are ever eager to point out they don't like the gritty mix because it doesn't hold enough water, are comparing it to their soils, which from the plant's perspective hold much too much water.

The gritty mix and the 5:1:1 mix hold just the right amount of water ..... to please the plant. Increasing the water retention of even the gritty or 5:1:1 mix by introducing fine particles comes at the cost of reduced potential for the plant, so comparing the convenience of the grower to the good of the plant is a little like comparing apples & oranges.

Those that aren't willing to trade a little more frequent watering for a more vital plant should probably stick with soils like MG et al. Growing well doesn't happen by accident or by luck. It comes as a result of not being afraid to do a little homework, trying something that might not seem altogether conventional at first glance, and not being put off by a little effort or inconvenience - and those are exactly the kind of people I like to surround myself with.

You guys may not see it yet, but your excitement and enthusiasm are self-perpetuating. I share it, others reading your offerings share it and in turn are motivated to follow in your tracks, which yields a second generation and a third ..... of enlivened growers.

Have fun - experiment - ask questions - help others see what you see. That's how these forums work best. If you want to share your thoughts about the contrast in what you WERE doing as opposed to how you feel about your newly chosen path, there's a thread on houseplants about MG soil where you can weigh in if you like. Telling me is like preaching to the choir. ;-)

Best luck.


Here is a link that might be useful: This one

    Bookmark   July 31, 2012 at 9:20PM
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Hi Al, bit of a different question for you here, although possibly answers to tomato questions would apply. I have been using Foliage-Pro for all my indoor container plants, and this year I have also been using it to feed some pumpkins. These are outdoors obviously what with the space requirements but for other reasons I had to keep them in containers. I used 8 gallon tall black plastic nursery pots, one per plant, and they seem to be doing very well, except for the need to be watered every day and twice a day if it's over 80F or so.
So my question is, these are being grown for their fruit, not foliage, and so I wasn't sure if the same tissue analysis reasoning would apply which says it is best to give them 3:1:2 ratio. My question, I suppose, boils down to: what is the ratio in a pumpkin fruit?
Because I'm about to run out of FP, and my vines all have lovely fruit growing now, so I want to maximize the growth of the fruits and minimize vegetation. I am wondering if I should just get more FP and keep using that.

    Bookmark   August 14, 2012 at 5:53PM
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When I first came on this forum I would have told you that you need a bloom formula to produce fruits. Tapla and others have showed me the real science. Plants uptake nutrients at a 3;1;2 ratio. Just using less will give you what you need. After growing a while you really see whats needed or not. I am so glad to be able to find this information, it has changed my outlook on fertilizers.

    Bookmark   August 14, 2012 at 6:14PM
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tapla (mid-MI z5b-6a)

There is little variation in the nutritional content of the various organs of any given plant. While you're told that N is for foliage, P is for roots, ..... - the fact is, the plant needs all the essential elements in roughly the same ratio for all it's parts. If you would like to curtail vegetative growth and promote the plant's allocating more energy to fruit production, simply reduce the N you're supplying. I do this by reducing the frequency of my applications of fertilizer and/or the strength of the solution, and by adding either KCl (potash) or Pro-TeKt 0-0-3 to the fertilizer solution. In essence, it changes my fertilizer ratio to something close to 3:1:3. It's important to understand that you have to ACTUALLY TAKE CONTROL of the N you're supplying and make sure you're creating a N deficiency to accomplish this goal. It's not the fertilizer ratio that controls how much N is delivered, it's the grower's hand on the watering can that contains the solution. Just changing the ratio to 3:1:3 won't do it if you continue to supply all the N the plant wants. The extra K is just ensuring there won't be a K deficiency if you are in control enough to keep the foliage a lighter shade of green, indicating your strategy is probably working. You'll probably be sacrificing some older and interior foliage as a result of your reduction in the amount of N you're supplying if it's working as you planned.


    Bookmark   August 14, 2012 at 6:37PM
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greenman28 NorCal 7b/8a

Thanks, Al, for clarifying that point.
It's one of the most common questions out there. Whenever you post one of these gems, I "clip" the post
for future use and reference. I thought that I'd read 2:1:2 at the Fig Forum...but was probably just
misremembering (memory is a poor servant).

I'll tag on another question, if I may: lately, the weather has been HOT....over 100°F frequently,
and over 95°F consistently. We're sitting on a hot week of weather to come, and I haven't fertilized
my plants for more than a week now. How do you fertilize when the weather stays hot in your area?


    Bookmark   August 14, 2012 at 8:52PM
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Awesome, thanks for the quick response!

    Bookmark   August 14, 2012 at 9:03PM
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tapla (mid-MI z5b-6a)

There's little difference between 2:1:2 and 3:1:3 when your focus is to limit the amount of N you're supplying. If you just reduce the amount of 3:1:2 ratio fertilizer you're supplying in order to induce a mild N deficiency, you're going to get a K deficiency to go right along with it. The extra K included when you cut back on the dosage of N prevents that likely K deficiency. When the ratio is 3:1:3, you just do a little more limiting. ;-) Instead of looking for a 2:1:2 ratio fertilizer that won't be easy to find, you can utilize the added versatility that an extra shot of K adds to your 3:1:2 ratio fertilizer, but you're still the guy in charge of the N supply, not the fertilizer's ratio. People lose sight of that all the time. They might say I use a 1:1:1 ratio fertilizer because I don't like all that N in a 3:1:3 ratio fertilizer, but they promptly feed the plant enough N to make it happy. They end up giving the plant the same amount of N either way - it's just that with the 1:1:1 ratio fertilizers it's impossible to give a plant enough N without OVER-supplying both P and K, but especially P.

I'm off on an adventure in the morning. A visit with my daughter & family, then on to Chicago for some fun at the Midwest Bonsai Show. I'll see you guys on Sunday.


    Bookmark   August 14, 2012 at 9:53PM
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greenman28 NorCal 7b/8a

Hey, Al!
I wasn't sure if your post was a response to my question. I'm certainly not limiting
my fertilizer, but am curious about how to fertilize when temps are so high. Should I
fertilize with lower doses more often? Or would you say to just fertilize regardless
of the temps?

Safe adventures, Sir, and a happy meeting with the fam and the Bonsai Show....
need I say, take lots of pics? ;-)


    Bookmark   August 14, 2012 at 11:43PM
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This is so great. As greenman said, this really is a "gem" of information.

So thats what makes the 3;1;3 ratio ideal for fruiting:
If your feeding a plant UP to what it can take in with the 3;1;3 ratio-Using a 1;1;1 you would be giving too much phosphorus by the time you even get close to giving all the N and K needs for full production.

    Bookmark   August 14, 2012 at 11:57PM
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tapla (mid-MI z5b-6a)

I cut way back when day temps go above 90* with any regularity. I got side-tracked and forgot to address that question - sorry, sir. ;-)


    Bookmark   August 15, 2012 at 9:05AM
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greenman28 NorCal 7b/8a

No worries! Thanks, Al!
I mixed up a weaker dose this morning and fertilized all my Citrus before the sun rose.
The leaves are yellowing on my Moro Blood Orange, and I just couldn't let it go any longer.
We're supposed to drop down to 98°F today, but that isn't much of a reprieve. Lightning
storms ignited several fires in the mountains, and so the smoke has been making things even


    Bookmark   August 15, 2012 at 11:59AM
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Ohiofem(6a Ohio)

This thread deserves a bump.

    Bookmark   January 26, 2013 at 6:14PM
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Al...I have a question? I am hoping you might be able to clear it up for me.

I have always believed it is the watering solution most important when it comes to container grown plants, right?
Then if I need to lower the pH in my watering solution to lower it from 8.5 which my water supplier provides, if the water supply also has Mg and Ca in it, then why would I still have to lime my 5.1.1 mix if the water already has a high pH and if it did provide these elements?
A bit confused on this.

There are many saying they shouldn't have lime their peat or bark mixes if they are in places like Arizona which supply hard water with a high pH already.

I don't know how to explain this to others. They think that liming their mix will only cause a further problem.
In fact, they ask me why I lime, then use vinegar to lower the pH. They tell me this is contradictory.


    Bookmark   January 26, 2013 at 7:25PM
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My goodness! I found my answer and well put Josh!

Thank you!!!!!!!

"Yes, the 5-1-1 mix - due to the variation in bark pH primarily - can have quite
a low starting pH, which is why the addition of Lime is favored to bring the pH up
into the target range, while providing Calcium and Magnesium in the proper ratio.
Once the mix itself is in a range conducive to nutrient uptake, we really need only
concern ourselves with the potential alkaline creep caused by basic tap-water and accumulating
solids from fertilization. Thus, it is a good idea to test one's water and one's fertigation
solution. Indeed, in certain parts of the country, tap-water may not need to be acidified".

Liming is a very good starting point.


    Bookmark   January 26, 2013 at 8:03PM
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Mike, in my own experience, a water test was very important. It indicated that my water is very hard and very alkaline. It has enough calcium and mag that I do not need to add these to my mixes. However, to counter the alkalinity, I must add 4 ounces of 33% sulfuric acid (battery acid) to each 100 gallons of water. I grow hundreds of trees in containers, and the acid makes a huge difference, expecially to plants that are in containers for more than a few weeks. There are some acidic fertilizers available, but acid is still required Good luck!


    Bookmark   January 27, 2013 at 1:21PM
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I hadn't previously spent much time thinking about the nutrition of my plants; but now the more that I read and the more that I am exposed to, the more I want to know.

Thank you Al et al. for the free education and entertaining discourse.

I just received my first bottle of FP in the mail and did a little analysis to see how the contents stack up to to Al's nutrients chart. Two questions popped out at me:

1) Sulfur isn't listed as on their "guaranteed analysis" chart, however the Mg is derived from magnesium sulfate so I'm guessing that means sulfur should be present at a similar ratio to Mg. Is this about right or should I be supplementing the sulfur?

2) I understand the convention of normalizing all the nutrient ratios to the nitrogen content. I also understand the reasoning behind using the 0.43 and 0.83 coefficients for determining the P and K percentages, respectively. What I don't quite get is why we are not doing the same for N. If the FP is 6.1% NO3- and 2.9% NH4+, shouldn't those also come with 0.23 and 0.78 multipliers? That would seem to make sense to me, but I'm sure I must be wrong b/c that would completely throw FP off of the whole 10:1.5:7 ideal.

I just dosed half of my plants so I'm hoping to start maximizing my plants' potentials!


    Bookmark   March 24, 2013 at 10:45PM
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i just joined this forum today and have read some of the information here and am so happy that there are so many people here helping each other out. i came here to ask a question about safe containers for fruits, vegetables and herbs and while reading posts here, realized that i am a complete novice when it comes to the nutrition of my plants. i container garden on a roof top in nyc and other than adding organic soil i purchase from the farmers market i have never fertilized. and i use tap water to water the plants. i have an 18 year old peach bush, - because it's in a large plastic pot, it doesn't really look like a tree - nectarine and plum. i've had decent yields over the years - small fruits but very tasty ones. and i bought a grape vine last year. to get to my problem - i would like to repot my trees and decided to make sure to get safe containers - i was wondering if water barrels would be a safe bet? these are available at https://www.usaemergencysupply.com/emergency_supplies/water_barrel_30_gallons.htm that have been approved by the fda. they are a bit too high though so i am considering scoring and folding them over and then use some sort of fencing to face them so they don't show the bright blue color... will the scoring compromise the safety issue, that is, if these are safe... grateful for all your help. thanks.

    Bookmark   April 16, 2013 at 1:32PM
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Ohiofem(6a Ohio)

These are rated safe for water and food, so I think you can be confident they are safe for fruits, vegetables and herbs. There are other choices that aren't so expensive and wouldn't require cutting down and adding drainage holes. For half that price, you could buy a smart pot online, for example. I suggest you start a new topic asking about large containers. Most veggies and herbs don't need containers that large, by the way.

    Bookmark   April 16, 2013 at 8:32PM
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edweather(Zone 5a/b Central NY)

bloomi, Those barrels are seriously expensive from that source. Last year I bought 3 of the 55 gal drums used from a guy on Craigs List for $10 each and easily cut them in half with a regular old saw. There are also white ones out there. Maybe it's worth a try on Craig's list or something before you shell out that kind of $.

As suggested above, maybe start another thread. Sorry to get off topic.

This post was edited by edweather on Tue, Apr 16, 13 at 22:29

    Bookmark   April 16, 2013 at 10:27PM
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nil13(z21 L.A., CA (Mt. Washington))

Bloomi, standard nursery containers are made of polypropylene and are therefore perfectly safe for growing food.

    Bookmark   April 17, 2013 at 6:18PM
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shazaam(NC 7B)

Does anyone have any thoughts on substituting langbeinite/K-mag (21% K, 10% Mg, 21% S) for epsom salt when fertilizing mixes without lime (and with a fertilizer that doesn't supply Mg)? The only big difference that I see is the K content and, in my particular situation, I could use the extra K anyway (my fertilizer is 30-10-10). Is there anything that I'm overlooking?

Here is a link that might be useful: Langbeinite

This post was edited by shazaam on Fri, Apr 19, 13 at 11:32

    Bookmark   April 19, 2013 at 11:26AM
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Thank you ohiofem, edweather and nil13. all great suggestions. the large containers are for the trees not the herbs and veggies. i will definitely check out craigslist. but i will be back here to get help to deal with the watering and fertilizing issues.

    Bookmark   April 19, 2013 at 4:11PM
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drew51 SE MI Z5b/6a

"Does anyone have any thoughts on substituting langbeinite/K-mag (21% K, 10% Mg, 21% S) for epsom salt when fertilizing mixes without lime"

I think it is a great idea, I myself use a similar product. I certainly will never use lime. I'm in the Detroit area and our drinking water is full of minerals and has a ph of 7.8. So in general I want to minimize the amount of city water I use. I try to use rain water, but I often use it all. Many of the plants I grow are acid loving or at least like a PH of around 6.5. In this thread someone mentions using the 5 1 1 mix and all plants are doing well except strawberries. And it's probably the hard water and the addition of lime. A huge mistake! Each gardener has to know all aspects of your area. Here it is not a good idea to add lime. It will raise PH, and the water does enough of that. Any minerals are already present in the water, or can be supplemented in better ways. I add sulfur to most of my plants because of what I'm growing. I only use lime for my in ground lilacs. Al's advice is excellent, but one needs to adjust to the plant's needs. Another example if you want great tasting tomatoes do not fertilize once flowers appear, besides decreasing amount of water.. So this method would definitely produce inferior tasting tomatoes, with smaller yields. As when the plants is slightly stressed it produces better fruit, and more fruit. With fruit trees I would not fertilize anywhere near as much as suggested, and you also want to control water intake. And this is for potted trees or in ground. If you want good fruit, and not watered down yuck, you should know how to water fruit trees.
Corn can now be grown in containers and this regime would not provide enough nitrogen for a decent crop. So this info is a good start, but that is all it is, a start...

I have house plants that are over 38 years old. I bought them in the early 1970's. Mostly cacti and tropical's.
I also grow many berry plants and have fruit trees too. I'm rather new to edible landscaping but have a base of experience from growing potted plants for decades. I grow fruit in ground, raised beds and in pots.

I use Greensense Sul-Po-Mag as a soil additive in new plantings or potting soil, 0-0-23 23% K2O, 11% Mg, 22% S.
You can add to existing plantings too.
I also use as an additive Azolmite, which can be added also to existing plantings but best used in new plantings
Maxicrop seaweed is also used in existing plantings.
For new plantings I always use Mycorrhizae Fungi . Gnarly Roots is a pretty good one with 9 different species to cover all bases.
Numerous fertilizers depending on what plant, as they all have extremely different needs.
Although none of these products will help you at all if you do not know the plants you are trying to grow. None of my cacti get any of these products. Just a simple fertilizer. Good light, good soil, and knowledge of plant needs is all I need to grow beautiful cacti.

    Bookmark   June 1, 2013 at 8:05PM
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Hello All,

Al, let me begin by saying thank you so much for this great post along with your Beginner's Guide and Container Soil and Water Movement Posts. They are indispensable resources and very informative! Many thanks for your generosity and commitment to sharing your knowledge with everyone here. (And that last statement goes to everyone else on this forum as well!)

I have a "how-to" question for anyone who can point me in the right direction. I just repotted several succulents about a week and a half ago so I will resume watering this week now that they have hopefully adjusted to their new home. I will also begin fertilizing using the 9-3-6 with micronutrients which many here have recommended. I had not been fertilizing prior to the repot.

Do I need to gradually work up to the target dosage (similar to how you slowly acclimate indoor plants when moving them outside)? For example, should I start with 1/2 tsp/gal for the first few waterings, then go up to 1 tsp/gal, and finally go up to the full 2 tsp/gal? Or am I good to just go with the target right away as the plant will only use what it wants? (As a side question, is 2 tsp/gal the correct dose for the growing season? And it typically drops to 1/4 tsp/gal in the off-season, right?)

Many thanks to everyone for your help!


    Bookmark   July 30, 2013 at 10:53AM
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four(9B (near 9a))

Regarding liquid concentrates:
Roughtly how long does unapplied portion of a prepared batch remain good?
In a pail or jar, for example.

This post was edited by four on Sat, Jan 4, 14 at 9:52

    Bookmark   January 4, 2014 at 9:14AM
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tapla (mid-MI z5b-6a)

It depends on what is in the solution/suspension, how concentrated it is, whether it's organic or synthetic, ambient temperature, how much light it's exposed to ......

I noticed you edited/deleted your original question; likely because you reconsidered and discovered the error wasn't in the original?


    Bookmark   January 4, 2014 at 12:56PM
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I skipped a bit of the science stuff in this post to get to the practical info, but I'll go back and read it soon - I love knowing the 'why' as well as the 'how' =)

You should consider posting a 'newbie guide' where you just link every thread you start! They're so helpful!

    Bookmark   January 11, 2014 at 11:42AM
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four(9B (near 9a))

>> Regarding liquid concentrates:
>> Roughtly how long does unapplied portion of a prepared batch remain good?
>> In a pail or jar, for example.

> It depends on what is in the solution/suspension, how concentrated it is,
> whether it's organic or synthetic, ambient temperature, how much light it's exposed to

N-P-K 12:4:6, solution concentration per label directions for maintenance feeding of small containerized plants, synthetic, inside kitchen refig. Jar lidded.

    Bookmark   January 11, 2014 at 5:28PM
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tapla (mid-MI z5b-6a)

In a refrigerator, it should last a long time - months. Out of the fridge it will start stinking in a week or two.

No bacteria grows in undiluted fish emulsion because there is a concentration of antimicrobial additives strong enough to prevent growth of bacteria and fungi. Once the solution is diluted with water, all bets are off. The antimicrobial properties of the diluted solution aren't sufficient to stop growth, so it stinks to high heaven.

When a synthetic fertilizer is the topic, the solution itself prevents microbial activity until it's diluted, at which point it can start growing ugly stuff. Refrigeration slows the process considerably, no matter what you are mixing.

Take a look below at the funniest thread I ever read on GW. ;-)

Here is a link that might be useful: How NOT to make fish emulsion .....

    Bookmark   January 12, 2014 at 2:51PM
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vanman23(6b/7a - OK)

This is my first post. I just mixed some 5:1:1 with the lime and Osmocote Pro. I am putting this into an approximately 12cubic foot cedar container on wheels. I will be getting a lychee and mango plants at the end of the month and will be putting them into their own cedar container.
Once planted, will I need to fertilize with FP or is the CRF sufficient until it runs out? I had thought that the CRF was for the nitrogen need of the decomposing pine bark. Thanks in advanced.

    Bookmark   January 15, 2014 at 9:00PM
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tapla (mid-MI z5b-6a)

If the plants aren't actively growing, or until they are, the CRF alone will be fine. Do you know if it has all the nutrients, other than Ca and Mg?

Did you build the planter?


    Bookmark   January 15, 2014 at 9:39PM
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vanman23(6b/7a - OK)

Thanks Al for the quick reply. The Osmocote Pro is supposedly the same as the Osmocote Plus except with a longer release duration. I don't know because I've never used Osmocote Plus, and it may have been discontinued. I've attached the ingredient list.

Also, it seems that I read on a previous post that for root development it was better to have a somewhat nutrient deprived soil. If that is the case should I decrease the amount of CRF by diluting with soil without CRF. Can you please comment.

Yes, I built the planters. I made them large assuming the bigger the better at least for trees.

Again, thanks in advance.

    Bookmark   January 16, 2014 at 10:06AM
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vanman23(6b/7a - OK)

Cedar planters on wheels.

    Bookmark   January 16, 2014 at 10:08AM
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Oxboy555(Las Vegas)

Those are nice planters.

Be careful of:
a) staining your concrete
b) pushing them over seams in your drive/walk ways - especially once they're all heavy full of soil, water and plant material. If a caster gets caught, you can snap it right off. Don't assume they will just roll nicely over any crack, seam or change in elevation. Take my word on this one. :)

1 Like    Bookmark   January 16, 2014 at 1:19PM
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Ohiofem(6a Ohio)

Those are gorgeous planters. Sadly, the Osmocote Pro isn't really much like the old, discontinued Osmocote Plus 15-9-12. It has no calcium, and it contains urea. I switched to Dynamite All Purpose Select 15-5-9, which does have calcium and contains no urea at the suggestion of other forum members. I can't vouch for it yet, but it looks very good. I'll let Al respond to your questions about what to do now.

    Bookmark   January 16, 2014 at 1:28PM
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vanman23(6b/7a - OK)

Thanks for the compliments on the planters. I will be now be parking them on some brick pavers on the lawn once the warm weather starts. Good advise about pushing over cracks. I used 3.5 inch lag screws for the casters but that cedar is not that strong.

Ohiofem, I wish I had done more research on the CRF before I got the Osmocote Pro. Live and learn.

    Bookmark   January 16, 2014 at 3:51PM
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hairmetal4ever(Z7 MD)

OK - question. If I'm using Dynamite All Purpose Select when I make my mix, if I plan to feed with a solublle fert like Foliage Pro on top of the Dynamite, do I use the strength recommended on the Dynamite bag, or something less than that?

    Bookmark   February 4, 2014 at 9:41AM
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greenman28 NorCal 7b/8a

I would use the strength recommended on the Dynamite, and then reduce the soluble fertilizer rate (which is much easier to control). That's how I do it with Osmocote and Foliage Pro.


    Bookmark   February 4, 2014 at 11:06AM
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I have an oddly similar question. The media used for some of my plants claims to "feed plants for up to 6 months". I intend to use a constant low strength dose of liquid fert 12-4-8 or 9-4-9 with every watering (1tsp per gallon). How do I compensate for the CRF already inside of the mix? More specifically because there are different types of plants with different nutrient draws, is there a way to tell when the CRF is "used up"?

Also, how does this apply to the osmocote in the 5-1-1 mix?

    Bookmark   February 4, 2014 at 12:52PM
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Oxboy555(Las Vegas)

Go easy on the liquid fert, like Josh said.

There is no way to tell unless you cut off the liquid fert altogether and wait for your plants to show visible suffering or yellowing. I don't advise this.

Depletion rate of CRFs is based on temps and watering rates primarily. Where do you live? If you live in the desert southwest, that "9-month" CRF you added in spring to your outside containers will probably only last 3-4 mos tops into summer.

All things being equal, my CRF schedule is mostly a nice full feed in spring (whether a new batch of mix or existing), then another light later feed in summer. "Heavy" feeders like roses could benefit from another light feed in fall.

    Bookmark   February 4, 2014 at 1:30PM
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I just made a first small batch of 5:1:1, and I'm trying to decide if I want to add the Osmocote CRF to it or not. I am repotting a houseplant to give to a friend, so I should probably just add the labeled recommendation for individual repots? I receive my FP in the mail today, so I am inferring that this is the best way to go for the dozen or more plants I will be repotting for myself in both 5:1:1 (mostly for my houseplants) and 1:1:1 (bonsai and prebonsai). I have some young Japanese Maples that I rescued from the backyard, but don't know if I should transplant them into 5:1:1 or 1:1:1? They are in the worst soil EVER right now and have been since last summer. Can I bare root them now or is it too soon? How would you fertilize them? I have been reading these forums and other research for months, ad have many different fertilizers, but I didn't realize how wrong I was doing everything until I read these forums and Al's information which helps me understand.
I.A.W.T. (In Al We Trust).
Mikey G, Delaware

    Bookmark   February 6, 2014 at 1:24PM
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Oxboy555(Las Vegas)

Yes, you should sprinkle in some CRF, especially if you think the friend won't be diligent with liquid ferts down the road. How long do you realistically think this friend can maintain your gift?

Lots to consider in the 5-1-1 vs Gritty options, each with pros and cons (few as those may be). I don't grow JMs so somebody else here can comment.

    Bookmark   February 6, 2014 at 2:16PM
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tapla (mid-MI z5b-6a)

MLG - You should try to use soils you add CRFs to within a couple of weeks of adding the prills. This is because the fertilizer will continue to leach into the soil until it'd depleted, so high EC/TDS can be an issue.

Can I assume the maples are dormant? If so, keep them BARELY damp & repot at the first sign of bud movement. I would use the gritty mix unless all I had was the 5:1:1. You can be fairly aggressive with the roots of maples, and bare-rooting isn't a problem.


    Bookmark   February 6, 2014 at 3:03PM
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I feel like I just met a celebrity. Al, I'm just going to say I agree with every compliment you have gotten over the last 9 years or so, especially with how you explain the science behind your methods and being patient with beginners. I.A.W.T !!
I didn't know what Bonsai was until last spring, and immediately caught 'the bug'. I'm obsessed, and it's all I do unless I'm working (actually- even when I work, which I should have been doing today instead of mixing 5:1:1 ingredients that I've been screening and cleaning for 3 days). I made my 1:1:1 gritty last week, so I have everything I need to fix past mistakes EXCEPT for spring!
Al- ok I remember what you said about the CRF releasing into the soil and how, but what are 'prills'? Is that the lime? I bought a big bag of pelletized dolomitic limestone, but now I can't find where I read if it needs to be powder or pellet. (Finding formerly read informative posts is my main problem, and it's not easy to find the 'Container Soils' forums posted before 2009 for some reason.)The maples are dormant, but keep in mind I didn't discover how insightful these forums are until about a month ago. These jap maples (along with others) have been in a mix of potting soil, planting soil, soil from my yard, fine sand, vermiculite, a little perlite, and multiple different fertilizers, and other ingredients. I used to fertilize A LOT. I thought I was ingenious by putting clear poly- plastic around my screened porch, until I got to that chapter around early December. I soon after regretted disregarding the 'outdoor plant' literal definition, but I thought how could freezing weather be better than a "greenhouse" with limited fresh air and fluctuating temperatures. I would keep it heated during the day and let it freeze at night. So now I keep it heated enough to where it won't go below 45* at night, and it's about 60* during the day. I have 10 grow lights scattered about for my ever growing collection. Amongst many others are a 22 yr old Dawn Redwood, 10 yr old Chinese elm, a couple Juniper Nanas, etc... As I understand, they could very possibly have a sap flow that could freeze their cambium and kill them on account that they're probably really confused. Does this sound right? I always feel bad plants that are simply labeled 'BONSAI', at the Superstores or grocery stores, with their glue and inappropriately sized containers, so I buy one about every week. Although, I think some could have potential one day. It's hard for me to get precise answers to my unusually uneducated problems. I have too many plants and too many questions and perhaps you can point me to a more appropriate forum to find answers or ask the random questions.
Back to the issue, my favorite of the jap maps is the one that's over potted and suffocating. I'm not sure it's even with us anymore. But the one next to it in the same pot still has reddish shoots even though I tried my hand at grafting on it. The small pot on the left was uprooted by my cat 2 weeks ago, and I repotted in an aerated soil (you can see more perlite); I think it has hope. I stopped over fertilizing and watering as I became more educated. But when can I expect budding, early April? And do they have that long? I guarantee the roots won't look anything like yours. If the shoots turn black, is it definitely another departed stiff?
I just heard back from a bonsai society, but I have no idea when their next (my first) meeting is. I am the only person I know around my area with a fascination for plants and particularly bonsai around here. I'm excited to finally be able to join a bonsai club, but time is of the essence here and I got my famous Al's recipes mixed and ready to go.
Sorry for the rambling...I may be a bit over excited.

Ox- I am giving a ponytail palm (rescued from Costco) to the only friend who shows an interest in my hobby, and I am probably right to assume she won't fertilize unless I tell her to.

Any advice is appreciated, and thank you everyone for the personal knowledge and experience that you post. I have been trying to put together pieces of other peoples' situations to apply to mine, but it's soooo exhausting. Especially when I have to sift through posts like this one.

I heart all of you,

Mikey G
Former Tree-Murker
Future Bonsai Master

    Bookmark   February 6, 2014 at 5:45PM
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Oxboy555(Las Vegas)

Prills are the pellitized spherical granules with the hard coating that gradually release its fertilizer contents through osmosis. The thickness and ingredient of the prill coating determines release rate.

    Bookmark   February 6, 2014 at 6:43PM
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So prills are the CRF? I'm confused still....lime? Is pelletized lime what I should be using?

    Bookmark   February 6, 2014 at 7:32PM
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Oxboy555(Las Vegas)

Prills are mainly the CRF. You want that lime working fast so you want lime granules, "pellets" or powder. The Epsoma "Garden" brand you find at big box is fine. It may be pelleted but I don't think it's prills, if that makes sense.

    Bookmark   February 6, 2014 at 7:55PM
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Ok, I get it. Your the man, Ox. Al's phrasing just confused me a little bit.
I just picked up some Hydrated Horticultural Lime. It is a powder, and says add 1 tbsp per gallon of water once a year. So now I'm starting to think, I should stick with pelleted dolomitic lime, which only has directions for tilling lawns. They're gray pellets, without prills. The hydrated lime would flush out I would think. Perhaps I'm confusing my mixes again. There's a lot to this game. It is weird, though, how suddenly all of these different products in the gardening sections are starting to make sense to me, and even become relevant!

Thanks homeys!
Mikey G

    Bookmark   February 6, 2014 at 8:44PM
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Oxboy555(Las Vegas)

You don't want the horticultural lime. Stick with the dolomitic.

    Bookmark   February 6, 2014 at 9:00PM
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greenman28 NorCal 7b/8a

No *Hydrated* Lime!!! I hope you haven't used it yet!

The best product is the fine-powdered Dolomitic Garden Lime, as Oxboy wrote. Dolomitic Lime does come in prill or pellet form, and it can be used, although it might not spread throughout the mix as quickly. It's not a big deal, though.


    Bookmark   February 7, 2014 at 12:10AM
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Thanks guys, I did not use the hydrated lime. I read about the difference. I am taking the pelletized dolomitic lime and crushing it up a bit so it's more of a powder.
Ok....I'm doing it now....here I go....no turning back!
Haha, I heart my little trees!
Smell y'all later,
Mikey G

    Bookmark   February 8, 2014 at 3:22AM
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This and the Container Soils XX posts are just totally clicking with me. Making me want to switch from Graphic Design to botany! I've long been a little plant-obsessed (my family is full off avid gardeners and former farmers), but the more you get into the gritty details the more I think I'd like to really study this.

Since moving into a smallish apartment and having to switch to indoor container gardening (from outdoor, laissez-faire instinctive gardening) I've been struggling with fungus (and the gnats that come with it) for a while. I suspected it was the soil I was using (I've been mostly using miracle grow potting soil), but didn't really know what to do. I have been lurking on this forum for awhile, but after reading through this and the soils post I just had to comment and give a hearty thanks for all your patience and sharing that wealth of knowledge with us.

I have a big overtime check coming next week and the weather is getting cooler every day, so I think it will soon be time to mix up my first attempt at your 5-1-1 and re-pot my tomatillos and tomatoes (I've been wanting to experiment with keeping them over winter ever since I heard they are perennial in their climate - I have a VERY sunny bedroom with full-length windows and ample artificial lighting) and my poor, fungus-riddled houseplants (which are also all vegetables - celery, cayenne peppers, purslane, and onions). Knowing exactly what my plants need, on a cellular level, makes a huge difference in the way I think about my plants and their care.

So...yeah. TLDR; THANK YOU, I think I may have to consider taking some biology / botany courses at my community college now to feed the beast that is my hungry brain, and immediately re-pot all my poor sad plants.

This post was edited by happybana on Fri, Aug 8, 14 at 11:14

    Bookmark   August 8, 2014 at 11:13AM
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Oxboy555(Las Vegas)

You can still get some gnats with 5-1-1 but I bet the fungus problems go away.

Once you try out 5-1-1 or Gritty, you will never go back to Peat Pudding.

    Bookmark   August 8, 2014 at 11:37PM
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four(9B (near 9a))

> Posted by Oxboy555 Las Vegas
> with 5-1-1 but I bet the fungus problems go away.

Sure, in Las Vegas.
Try Orlando; here even gritty gets mold.

    Bookmark   August 9, 2014 at 1:12AM
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tapla (mid-MI z5b-6a)

HB - a cool post - it illustrates your enthusiasm, which is a contagion around here. We all feed off it!

Thanks for the kind words!


    Bookmark   August 13, 2014 at 8:51PM
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Well I've been reading all these posts from everyone here and I've learned a lot so far, but I still have a few questions.

I live in México so I don't have access to FP or many of the other fertilizers that people find in the US.

I just started gardening in containers and I've been using MG Liquafeed 12-4-8 which only contains NPK and Mn(0.05%) and Zn (0.05%)

Now since I started reading all these posts I've realized that my fertilizer is lacking most of the micro nutrients so I decided to look for a new soluble fertilizer that contains all the micros that I need.

Unfortunately here in México is not so easy to find several different fertilizers and the best I've found so far is one called Humifert, which said that has 10% N, 5% P, 5% K and then the next nutrients on a g/L base:

(Fe) 0.60
(Zn) 0.80
(Mn) 0.40
(Cu) 0.40
(Mo) 0.01
(B) 0.01
(S) 1.5
(Ca) 0.25
(Mg) 0.25

So what I did was check the facts sheet and realized that the liquid has a density of 1.2 g/L so with that I converted all the nutrients to a N base 100 like the one that I'm posting bellow.

Finally after doing that I realized that while it contains all of the micro nutrients that the plants need, some of them are way off from the requirements that Al mentioned in his chart, so I was wondering if I could use this fertilizer as a supplement while still using my MG 12-4-8 or do I need to find another fertilizer again?

Thank you very much!

    Bookmark   October 20, 2014 at 11:26PM
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Happybana: my 2 cents from past experience: stay away from Miracle Gro potting mixes. They sometimes have fungus gnats, and internet reviews indicate it's not an isolated experience. I'm sure it's not intentional, but it's frustrating.
5-1-1 mix can still have fungus gnats and mold, but it's a bit easier to control, even with my brown thumb. I found that adding a little bit of hydrogen peroxide to the water I use to irrigate with helps. Al has a chart somewhere, I'll try to remember to look for it later. I kind of wing it, somewhat to the tune of about 1tsp/cup peroxide/water, sometimes stronger, if the plant is healthy.
I've heard bleach works too, but I've not been brave enough to try that, and the problems haven't been bad enough to need it yet.

    Bookmark   October 21, 2014 at 2:20PM
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Loveplants2 8b Virginia Beach, Virginia


Just asked admin for a " sticky"


    Bookmark   October 25, 2014 at 2:54PM
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Another tasty gem of knowledge, thanks again to everyone's contributions!

    Bookmark   October 27, 2014 at 10:02PM
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pinusresinosa(MN Z4)

This is fantastic information. Thank you!

I've done a lot of trial and error over the years with feeding container plants. The starts I start in the spring on benches do well with a specialized commercial feeder mix, depending on the species of plant is being fed here. It simply gets applied at watering time.

At home however, I have many large tropical plants that live in pots that are brought inside and back outdoors over the season. I typically fertilize many of these plants regularly, as they all grow pretty fast year-round. It's hard for me to keep them satiated in a consistent fashion with liquid overhead feeding as I would for young plants in the greenhouse. I've tried many products. I liked Jobe's sticks for a while but it seems to me that those things have become more like plastic tubes than fertilizer. I started trying a new product this last spring and my plants are doing really well on these Xtreme Gardening organic feeder packs. The seem to release fast enough to keep hungry plants happy, but not so fast that I go through them quickly.

Even my indoor petunias love them.

I added a link just in case anyone's interested. :)

Here is a link that might be useful: Organic Feeder Paks

    Bookmark   October 28, 2014 at 2:55PM
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I read a lot about leaching of fertiliser out of the container before the plant can actually take it up. Apparently N is the first to be lost.
I saw on a bonsai site that the addition of humic and fulvic acid helps with the uptake of nutrients. It can be added to a very open substrate like we use to help with leaching and nutrient loss.
Any thoughts on this?

    Bookmark   November 10, 2014 at 10:04PM
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tapla (mid-MI z5b-6a)

Here is something I posted on the soil forum a while back. You might find it interesting, and your answer is 'in there'.

Humic acid (HA) is formed during the humification process (decaying/composting) as plant and animal matter break down. The main source of HA is lignin, which is the most common bio-compound on earth next to cellulose - it's what makes plants stiff. As the organic matter breaks down, it forms several acids called carboxylates and phenoxides.

While there are several acids formed during the breakdown of organic matter, While there are several acids formed during the breakdown of organic matter, the acids formed by a variety of decaying vegetable matter end up being pretty much the same group of acids in the same proportions. Further, it's not the acids formed during humification that vary with any significance, it's the compounds they form with free ions when mixed into (primarily) mineral soils. It's easy to envision why that is true when we consider that all plants are made up of the same building blocks (nutrients/elements) in almost exactly the same ratio. IOW, there is little difference, chemically speaking, between sequoias and snapdragons.

Also important to consider is that peat moss is made up of a combination of cellulose, lignins, and humic acids. This fact is probably what would allow any/all container media producers to lay claim to the fact that their product contains HA. As I mentioned upthread - advertisers often lay claim to things their research shows the general public might consider a huge plus, when it's an intrinsic part of all similar products. Shell Oil used to advertise that their gasoline contained lead to guard against spark knock, when in fact all gasoline used to contain lead. If I thought a little, I'm sure I could quickly come up with another dozen examples more current.

I'll leave an answer I posted to a thread on the container forum back in Nov '08. The question posed was, "Does humic acid serve any purpose for container plants?"

I drew a delineation between mineral soils and container media primarily because the immense volume of organic matter in almost all container media. This would even include the gritty mix, which has a 1/3 organic component - roughly 6-10 times what you would find in most natural and garden soils. Hopefully, we have built or are using container media with a suitable structure, but even if we were not, the type of structural improvements usually associated with the use of HA in mineral soils do not apply to container media. Where container media is concerned, if the structure is not there from the beginning, the only way you can add it is by adding enough soil particles of the size required to physically achieve your objective, You cannot change container media structure by adding HA or its associates.

The reply to the question (about plants in containers) I mentioned a little upthread:

Humic acid (and its accompanying fulvic acid) are most often used as an amendment to improve the quality of clay soils, sandy soils, and/or other soils organically deficient. The primary value of adding humic acid to clay or other compacted soils comes from the resulting structural break-up (increase in friability) of these soils. Obviously, this should not be an issue in the soils you are using. In sandy soils, humic acid's value is in its addition of organic material to soils, which would also in the end improved water retention and root function, neither of which are anything you would be lacking in the soils you use.

In some soils, humic acid can also play another role in facilitating a plant's ability to assimilate nutrients. Humic acid can lower pH and help unlock otherwise bound nutrients in the soil that might not be unavailable under conditions of higher pH. Again, this should not be an issue for you, given the fertilizer regimen you use and a known favorable pH.

Finally, humic acid can stimulate soil micro-biology in some soils, increasing the numbers and activity levels of soil micro-populations, the primary function of which are to make available minerals and nutrients which could be stored within the humic acid complex and hopefully available on an 'as needed' basis. Again, not much of a benefit when you consider you're supplying a full compliment of nutrients in a readily available form on a regular and 'as needed' basis.

I suppose if I was to sum it up, I would say that a build-up or adequate measures of humic acid in garden soils is to be desired & most effectively accomplished by the regular addition of organic materials to the soil. How valuable wholesale applications of humic acid are to garden soils is probably highly variable by soil type, soil composition, and the intrinsic quality/value of the individual product at hand. It's value in containers would probably be extremely marginal at best or go completely unnoticed (as it did when I tried the product for my container plantings several years ago) but there's nothing to stop you from trying it.


    Bookmark   November 11, 2014 at 9:44PM
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Hello all. Not sure but I think you guys are all dealing with bonsai here. But more generally, for containerized production/growth of plants outdoors, I've not been very inclined towards humic acids, compost teas, etc. simply because we use compost itself as a regular part of our mix. Here, I'm talking large-ish planters with ornamental display plantings-flowering stuff, foliage plants-during the growing season only, here in Wisconsin.

Our tap water, coming from a large hard water lake, is full of calcium/magnesium. I don't add lime to anything, because of that fact. I use something like Osmocote T-14 as a light background addition, kind of like somebody up above said-if it rains a great deal, we want to have some kind of nutrient charge in that mix. But the mix also contains actual topsoil. As such, both water-holding and cation-holding ability is far beyond typical soilless mix. Then too, I like to tank mix an "acid special" type of water soluble into pretty much every tank of water we send out, but at a very low, spoonfeeding rate. More than one product might get used for that purpose, but bottom line, we're talking only perhaps 50 PPM N. Very light. This does seem to help, and as the summer drags on, I believe that initial CRF charge is pretty much gone anyway.

Some of the most common flowering herbaceous species-think petunias-are acid lovers. It is most helpful to simply observe foliage coloration when trying to ascertain proper fertility levels. And at that low, low constant feed rate, we've never ran into the problem of burn or overfertility, especially of N, which would tend to leave us with lots of vegetative growth and few flowers, or still worse, proneness to pathogens. IOWs, so far so good!


    Bookmark   November 13, 2014 at 1:14PM
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I stay in Wellington NZ and have been doing container planting for bonsai (mainly) for the last 6 yrs. The last 4yrs i'm using only Foliage Pro that I imported from the USA. Mainly because of the weather (or so I though) the growth has been really slow. It frustrated the hell out of me. I was beginning to think that FP was over rated as it really made no difference. I stay up a mountain and I also had the thought that its because of the altitude that the plants don't grow. They seemed just hung on with very slow growth.
I have always been using gritty and 5.1.1 mixes with pumice, composted pine bark and granite grit. I also mix in sphagnum moss for water retention for some plants.
Before the beginning of this growing season I read about humic acid on a bonsai forum. This following extract is what got me going on it....

"The application of Humic acid to a watering regimen insures that this CEC union is kept. Humic acid ensures that our mix will continue to stay negatively charged and attract and HOLD the fertilizer ions"

I thought that makes sense and got me some liquid humic acid. I now add it once per month in a diluted form. After 4 months (4 additions) EVERYTHING is growing faster than their usual rate. I'm smiling from ear to ear. Some plants have grown more in this 3 months than the whole of last year. I have a Satsuki planted in pure pumice. It to has been going so so, but so far its going bonkers. I give it humic acid to.....
That leads me to believe that all those years most of the fertilizer washed out before the plants could take it up properly.
I really have no other explanation as this is the first year I see a radical difference, and can only put this down to humic acid, because that is the only thing I have been doing different.
I'm very excited for the rest of the season ahead. I have got some self respect back again ..... :-) :-) :-)

This post was edited by fredman on Sat, Nov 29, 14 at 0:10

    Bookmark   November 28, 2014 at 6:51PM
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drew51 SE MI Z5b/6a

In the first post of this thread it is stated "That is, they allow some things to pass through the walls, like water and select elements in ionic form dissolved in the water, while excluding other materials like large organic molecules

That's not really true. Large organic molecules can pass through cell membranes. Including those used for food. Nutrients do not have to be broken down to basic elements.
An example is glyphosate, aka Roundup is a molecule with 15 atoms. Still rather small, but is easily transported across cell membranes. Pesticides would be rather ineffective if they could not pass cell membranes. Somebody needs to go back to biology class.

Many large organic molecules are actually broken down inside the cell. . It is a myth that organic fertilizer needs to be broken down by bacteria for basic elements to pass through, it does not. Bacteria though are needed to break down very large proteins into amino acids before being absorbed, but not into elemental N,P or K.
Even some peptides can be absorbed as long as they are less than 4 amino acids long. Much of this thread is just not true, I would disagree about the assessment of the availability from organic sources too. in general they are more reliable then synthetic sources, the opposite as to what is stated.

    Bookmark   November 29, 2014 at 9:23AM
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tapla (mid-MI z5b-6a)

Anyone here use glyphosate as a nutrient source??

Once applied and absorbed, glyphosate accumulates primarily in meristematic tissue, where it binds the active site of the EPSP synthase enzyme that is critical for the production of certain amino acids and other essential compounds that use the same pathway intosize> the cell, so it doesn't have to enter the cell do its business. Death of the plant ultimately results from lack of nutrients and dehydration a week or so later.

Most pesticides are topical contact killers. Systemic insecticides are absorbed into the plant where movement, like all transportable chemicals, takes place principally in the plant’s vascular system (phloem/xylem). Insects that partake of the toxic gallimaufry die of various causes, depending on the toxin.

I think you're probably right in your assertion that someone needs to go back to biology class.


    Bookmark   November 29, 2014 at 1:35PM
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Hi everyone!

Old time lurker, new poster here. I live in tropical Philippines, where it's really difficult to find non-organic fertilizer. I managed to buy MG 24-8-16 from a PX store, and some Epsom Salts from new age/wellness stores.

The one thing I'm having difficulty finding is calcium. There are no stores that sell garden lime or gypsum, at least for retail sizes (I've sourced a supplier of agricultural lime, but they sell to farms, in bulk quantities; I only have a small space for gardening, I won't be able to use 5 sacks of lime in a single lifetime.)

I did some research on retail products that has calcium in them, I'm wondering if I can use some of these:

-Dehumidifier pellets (calcium carbonate)
-Osteoporosis medicine (calcium carbonate)
-Calcium supplements (often with added multivitamins)
-Bread mold inhibitor (calcium propionate)
-Pool cleaner (calcium hypochlorite)

I know that garden lime is primarily calcium carbonate, so I'm wondering if those dehumidifier pellets or the osteoporosis medicine would work. I also thought of chalk, but I'm not sure if modern chalk is still made from limestone, and most of the available chalk don't list any ingredients at all.

Thanks in advance for your help!

    Bookmark   December 10, 2014 at 11:41PM
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tapla (mid-MI z5b-6a)

Are you in need of a Ca source for a container medium? What is the medium composed of? If it's mainly coir or CHC's, dolomitic (garden) lime wouldn't be appropriate anyway. You can always use CaSO4 (gypsum) as a Ca source, and that won't noticeably affect pH levels, either.

CaCO3 isn't soluble, so unless it's very fine, you're not going to get much Ca from it. The Ca supplement is probably CaCO3 (soluble in stomach acid), and won't be much help, and many are high in Na, so not appropriate for plants. Ca(ClO)2 would be toxic to plants and even small quantities can drive pH upward quickly.


    Bookmark   December 11, 2014 at 3:36PM
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nil13(z21 L.A., CA (Mt. Washington))

I have to go with Drew on this one. Plants can take up larger organic N molecules. There are a bunch of transports for them with new ones still being discovered. It seems to be a trait evolved to reclaim root exudate. There is also evidence of translocation of dissolved organic nitrogen (DON) to leaf tissue for N storage. Now there is a lot of debate on this topic. There are questions about how much is actually available due to microbial competition, it may only be useful in inorganic nitrogen (IN) poor environments, and it goes on from there because this is fairly new ground. All sorts of molecules can pass through plant cell walls (with or without transporters) and even be translocated. That is how systemics work. Determination of the rate of diffusion through the cell takes into account pH and charge more than size (some of those herbicides are pretty big).

    Bookmark   December 11, 2014 at 8:57PM
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tapla (mid-MI z5b-6a)

But neither systemic insecticides OR herbicides need to enter the cell to do their job, and what is organic N? There's nothing in the latest edition (2012) of Marschner's Mineral Nutrition in Higher Plants to support this. I spent a long time looking before my last post.


    Bookmark   December 11, 2014 at 9:21PM
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nil13(z21 L.A., CA (Mt. Washington))

This seems to directly contradict what you are saying about herbicides.

Here is a link that might be useful: Herbicide absorption

    Bookmark   December 11, 2014 at 11:17PM
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nil13(z21 L.A., CA (Mt. Washington))

Here is info on organic nitrogen

Here is a link that might be useful: Amino acid uptake in plants.

    Bookmark   December 11, 2014 at 11:24PM
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Thanks for your help, Al!

Yes, I'm trying to find a Ca source for container plants. I'm planning to use a modified version of the gritty mix for my new batch of native chillis and citrus. My chillis died drowning in their soil (composed of coco coir, compost, and carbonized rice hull) last rainy season. So I did some research on free-draining soils, bumped into your posts here on GardenWeb, and here I am.

I already bought a bag of ZooMed Reptibark, sourced some scoria and pumice, and there's a hardware just a street away that sells grit/gravel of all sizes. I still need to find a replacement for turface. I can't find floor dry or calcined DE, so I was thinking of three options: using hydrocorn (which are ridiculously expensive), increasing the amount of bark in the mix for more water retention, or just not using gravel/grit at all so all the components take up water.

Can't find garden gypsum here, unfortunately. Calcium is the only component missing for the fertilizing regimen outlined in this thread. The only gypsum known to stores here are gypsum boards, used for construction.

I can buy pure CaSO4, but it's for beverage processing and other industrial purposes. And they sell it in 50kg batches; unless I'm starting a farm, I don't think I can use that all up.

Plaster of Paris is another one that has CaSO4, but I didn't bring it up initially because it's probably a stupid idea, as it will probably cake up and solidify.

Thanks again for your help! I've learned a lot these past couple of months because of your informative posts!

    Bookmark   December 11, 2014 at 11:49PM
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drew51 SE MI Z5b/6a

But neither systemic insecticides OR herbicides need to enter the cell to do their job,

Do not they have to enter or at least pass through a cell membrane to get into the plant? I guess enzymes control portals to make wide holes for larger molecules to pass if they cannot pass though passively. They may be intercellular versus intracellular, all the same they have to pass through the root or leaf cell membrane at least.

I have always be fascinated by biological molecules. The process of digestion, and also protein synthesis. When one says molecules one often thinks of water and other simple molecules, but enzyme molecules can have 400 thousand atoms or more, and it's one molecule! Amazing complex molecules one could spend a lifetime studying. I also find the transcription of DNA and RNA fascinating too. Huge molecules unravel the DNA, act as a template for whatever molecule is being read and created from the map of life, It's simply amazing to say the least.
Viruses are fascinating too, DNA or RNA wrapped in a protein coat. This is alive? Well yes, by definition it is.
It steals a cells ability to replicate DNA to reproduce itself. it also can insert itself in other cell's DNA, and take some for itself. Some flu viruses are 90% human DNA.
Viruses are not the smallest form of life. Viroids are. An even smaller RNA circular chain with no protein coat. They can be 1/4 the size of a virus.

    Bookmark   December 12, 2014 at 1:38AM
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use of plaster of paris was mentioned on this thread (& probably some other too):


    Bookmark   December 12, 2014 at 1:09PM
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removed dp

This post was edited by rina_ on Fri, Dec 12, 14 at 23:05

    Bookmark   December 12, 2014 at 1:10PM
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Thanks a lot, Rina! Turns out it wasn't a crazy idea after all!

Just wondering: why doesn't the Plaster of Paris cake up and solidify in the container? Is it because the amount is so tiny compared to the volume of water? Or is it because they're mixed in with other particles?


    Bookmark   December 13, 2014 at 8:31PM
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tapla (mid-MI z5b-6a)

When you add water to H2SO4 it reacts to form calcium sulfate dihydrate (H4CaO6S, I think). The dihydrate molecule is larger, as well as more stable. As the larger crystals form they grow into each other. and interlock. It's the interlocking of the crystals which causes the powder to harden. The last pieces of the puzzle are easy to see, so I'll skip that part.


    Bookmark   December 13, 2014 at 8:56PM
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