A Soil Discussion II

tapla (mid-MI z5b-6a)August 25, 2008

A previous thread on the same subject had topped out at the limit of 150 posts. In case there is additional discussion or more questions, we can continue here. The text repeated:

A Soil Discussionsize>

Ive been thinking about what I want to say about soils here, and how I should open. IÂm going to talk a little about soils primarily from the perspective of what is best for the plant - not the planter. ;o) More often than not, the two ideas are mutually exclusive, and the plant suffers loss of vitality for grower convenience. There is absolutely nothing wrong with that. Probably none of us can afford the time it would take to give our plants the best care possible, and we need to decide on an individual basis, how much attention we can pay our plants. IÂll explain later.

Let me start by saying that whenever I say Âplants I mean a very high % of house plants and freely allow that there are exceptions to every rule; but, we need to learn the rules before we can recognize the exception. IÂm going to offer a few (of what I think are) rules I believe are difficult to challenge, and that IÂve adopted in my growing practices after a fair amount of study and consideration. IÂm going to leave light levels out of this conversation after acknowledging that they are probably just as important as soil to a planting, the difference being, we can recognize and change poor light levels easily if we choose, but poor soils are not so easily remedied.

Rule: Plants need air in the root zone as much as they need light and water. The soils we usually buy in a bag either do not supply enough aeration from the outset, or they do not supply it for a long enough period. Most, or at least many readers are expecting their plants to live in the same soil for several years, when the fact is that most peat based soils substantially collapse within a single growth cycle. That is to say that the peat particles break down into continually smaller pieces. This reduces the number of macropores (large air pockets), causes compaction, and increases the amount of water the soil holds in root zone and increases the length of time it remains there.

What does this mean to our plants? Well, there is the specter of root rot, but even if we set that aside, there is something more subtle occurring. Whenever roots are deprived of oxygen (O2) they soon begin to die - incrementally. First, and after only a few hours in saturated conditions, the finest roots that absorb water and nutrients begin to die. Already, the plant is operating under stress. Gradually, thicker roots die unless the plant uses the water in the root zone or it evaporates and O2 is allowed back into the soil. When adequate aeration is restored, the plant is disadvantaged, because fine rootage has died. The plant begins to regenerate the lost roots, but guess what? It has to call on energy reserves it has stored because the roots cannot efficiently take up water and the building blocks from which it makes food (nutrients/fertilizer). This stored photosynthate that goes to root regeneration would have been used to increase biomass - flowers, fruit, foliage, stem thickness. See how subtly aeration affects growth?

Rule: Our number one priority when establishing a planting should be to choose a soil that guarantees adequate aeration for the expected life of that planting. We can easily change every other cultural influence if we choose. Light, temperature, nutrients, moisture levels Â.. all can be changed, but we cannot change aeration, so we really need to consider that as a priority.

It is here where we need to bring attention to the fact that, as alluded to above, convenience has costs. IÂm not saying that in chiding fashion. I simply want to make the point that when youÂre able to go several days to a week without watering, in a high % of cases, the cyclic death and regeneration of roots is taking place. The plant is growing under stress and is weakened to varying degrees, depending on the severity of O2 deprivation in the root zone.

Rule: A fast soil that drains freely will be far superior from a plant vitality perspective than a more convenient soil that stays wet. The cost: YouÂll need to decide if youÂre willing to water and fertilize more frequently to secure the added vitality.

I could go on for days about soil, but IÂm hoping that IÂll be able to discuss HOW we can get to a better place with regard to our soils through answering any questions that might come up, and exploring options. Before I close, I would like to talk for a minute about another bane of poor soils.

Many of us recognize what we consider the main danger of overwatering - root rot, and do our best to prevent it. Most often, itÂs by watering sparingly so the soil is never saturated, but let me explain what happens when we do this.

Plants best take up water and the ions dissolved in it when the ion level is very low. This ion level is measured by either electrical conductivity (EC) or the total amount of dissolved solids (TDS). Problems arise when the TDS/EC level is low, when the plant can take up water easily. It remains hydrated, but starves because there is not a high enough concentration of ions in the soil water. If the level of TDS/EC is too high, the process of osmosis is affected, and the plant cannot efficiently take up either water OR nutrients, and the plant can starve or die of thirst in a sea of plenty. ItÂs up to us to supply the right mix of all the nutrients in a favorable range of TDS/EC.

IÂm sorry to be a little technical, but IÂm getting to a point. When using soils that are not fast enough to allow us to water copiously and continually flush the salts that accumulate from fertilizer and irrigation water something unwanted occurs. If we do not flush the soil, these salts accumulate. This pushes up the level of TDS/EC and makes it increasingly difficult for the plant to take up water and nutrients.

Imagine: A soil that is killing our most efficient roots, which stresses the plant and makes it more difficult to take up water due to the lack of those roots, while it insures that the level of TDS/EC will rise, making it difficult or impossible on yet another front for the plant to take up water and nutrients. Is it any wonder that our plants start to struggle so mightily toward winterÂs end? Are we really seeing the effects of low humidity or do you think it might be drought stress brought on by either an inappropriate soil or less than favorable watering practices? Probably a little or a lot of both.

Rule: Whenever you consider a plant in trouble, you must consider not only the plant, but the rest of the planting as well - including the soil. The insect infestations, diseases, and stress/strain we so often need help with here, can almost always be traced back to weakening of the organism due to an inappropriate soil (or, as noted, inadequate light - though in an extremely high % of cases, it is indeed the soil).

This only touches on the cause/effect relationship of the soil to the planting. If there are questions, IÂll try to answer them. If there is disagreement on a point or points, IÂll offer the science behind my thinking and you can decide individually if the things I set down make sense.

I would strongly urge anyone who wasnÂt long ago bored to tears to follow this link to another thread I offered on the container gardening forum. If you want to get into the science and physics of what happens to Water in Container Soils

, follow the embedded link. You'll also come away with the knowledge of what makes a good soil.

I hope this starts a lively discussion and provokes lots of questions, but more importantly, I hope it eventually, and as the thread progresses, helps put a few more pieces of the puzzle together for at least a few forum participants. ;o)


Click here to link to previous thread

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arjadiejai(WNY z6)

Thanks for answering my questions on the older thread!

For the terrariums, I'm interested in a purely academic sense, but at this point definitely not something I have the time/money/effort to get into right now. You know how those ideas are always floating around in the back on one's head!

Thanks again!

    Bookmark   August 25, 2008 at 8:59PM
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In the interest of keeping the message of less length, Al is going to reprise a sequal to War and Peace and include his thoughts on all the dirt he has picked up from others.

    Bookmark   August 25, 2008 at 11:37PM
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I couldn't open the other thread, it took forever to load on my PC so I'm very glad Al started the second thread here.

I just have a little story on using the gritty mix Al recommended that I'd like to share. My growing condition may be entirely different from any of yours but here goes anyway.

I live in Saigon, a hot and extremely humid environment. For a very long time, my late mother always wanted to plant a pepper plant (or chilly?) so that she could pick fresh pepper from the garden for meal. But she could never have any pepper plant to maturity. The reasons the plant - one after another as she tried to plant them - died were not known, until recently when I joined GW. I guess they died, within a month or two after being planted, because:

1/ we always planted the seedling plant in a TOO BIG container thinking that a lot of soil will help the seedling grow strong;
2/ we used common garden soil + a lot of composted cow manure, thinking that garden soil was ok for container and cow manure would enrich it even more and would make it better for the plant;
3/ we watered the plant every day, except on rainy days, so that literally meant the plant was watered every day of the year.

When I first knew about Al's gritty mix, I wasn't interested because "turface, pine bark, perlite" were non-existence in Vietnam. But after too many fails at planting my flowers and especially "the pepper plant" and after reading so many success stories about the mix, I thought I might try it. So I started looking around for substitutes.

I thought the main idea of Al's mix is aeration to promote root growth. Since we have abundant rainfall here, and also I'm a pensioner, watering is not a big deal, I felt much more confident to use a more porous mix for my container plants. I substituted "turface+pinebark+perlite" with "coconut husk chips+crused charcoal+dried rice husk" and replace CRF with another commonly found type of NPK fertilizer here. (I don't have gypsum, however)

Since I used this mix, my plants look a lot happier and especially my ever-wanting pepper plant! It grows so lush and produces a lot of "fruits"! I wish my mom was still around to enjoy fresh pepper!

That's my story. I'm sorry if I have bored you though!

Xuan (from Vietnam)

    Bookmark   August 25, 2008 at 11:59PM
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It's a great story, Xuan! It proves the theory behind the idea... even though you used substitutes, you got the desired results!

I've got much healthier root systems on my plants, too, now that I know what the relationship is between plants, soils, proper watering, fertilizing, air circulation, etc...

    Bookmark   August 26, 2008 at 12:12PM
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j_nail(5 Eastern WA)

Your substitutions are essentially right on the money Xuan! It is my understanding that coconut and rice husks have been under investigation (or have been used in the past??? I forget...) as more renewable and readily available alternatives to perlite to improve soil aeration in commercial soil mixes. I can't quite grab what is lingering at the back of my mind in regards to charcoal at the moment...will check my notes when it's not past my bedtime!

    Bookmark   August 27, 2008 at 1:59AM
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Charcoal, as I understand it, absorbs chemicals and keeps the soil "sweet", but after a period of time, it's just a rock in the mix, so to speak, as it eventually stops working. Think about charcoal used as filters in fish tanks or air cleaners... that sort of thing. I don't know if it becomes completely inert, though...

Coco coir is a great product... it's renewable, and it tends to decompose at a very slow rate... however, it is processed with some kind of salt something or other, and care should be taken to make sure the product comes completely rinsed from the manufacturer, or you'll need to repeatedly rinse the stuff to remove the salts.

I hope I explained that all correctly! I think you get the idea, though... :-)

    Bookmark   August 27, 2008 at 11:50AM
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puglvr1(9b central FL)

Xuan, that is a great story, thanks for sharing it with us. Al has always said that these ingredients/proportions are not set in stone. Depending on where we live, climate,gardening habits and type of plants we want to grow. That's what is so great about his formula. There many different things we can use/substitute and still works great for the individual gardner. I personally have learned a lot from Al, and my plants health and vigor shows that. Glad you started a new thread, the other one is getting so long, it does take a while to load...Thanks Al!!

    Bookmark   August 27, 2008 at 12:29PM
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Are there any other substitues that would work that anyone can list for people that can not find the ingredients Al has listed? It would help a great deal:)

    Bookmark   August 28, 2008 at 8:07AM
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Thank you, Jodi, for the explanation. I've learnt from my fellow orchid growers to rinse both CHC and charcoal many many times before using them.

My mix consists of CHC + crushed charcoal + dried rice husks. With this mix, I water every day and fertilize every month with organic and inorganic fertilizers alternatively. My plants love it!


    Bookmark   August 29, 2008 at 11:47AM
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Well I finally got my grani-grit today. I seems like the perfect particle size. I now have all the ingredients for Al's gritty mix. Here is what I mixed up, about one gallons worth.

1 part turface
1 part soil conditioner
1 part grani-grit (growers)
1 tsp. epsoma lime granules

I also got the fertilizer I was looking for Peters Excel Cal mag 15-5-15. I mixed up 1 gallon per bag instructions and also added a few drops of Bio-Genesis Mineral Matrix Micro- nutrient supplement per bottle instructions. I couldnt get the earthjuice microblast in the size i wanted but the bio-genesis is just about the same thing. I do have a question though, should I be applying the fert and supplement at full strength per the bag instructions or should I be diluting it? Also should I fert at every watering or only 1-2 times a month? And do you have to water more frequently in the 1-1-1 mix? How many times a week would you suggest? They are out on the patio now in Charlotte NC Still hot and humid. They dont get a lot of direct sun though. Boy that water ran through it real fast!! heres a few pics of my mix and the dieffenbachia I,m trying to save. I had to butcher it to get rid of the rotting leaves. Do you think it can recover?

    Bookmark   August 30, 2008 at 4:51PM
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tapla (mid-MI z5b-6a)

Great job! I think you'll be really pleased when you get used to this soil. Look how much it looks like mine:

". . . should I be applying the fert and supplement at full strength per the bag instructions or should I be diluting it?"

With that soil, if you watered copiously, you COULD fertilize at the full recommended strength every other time you water. I'm not suggesting that you do, only making the point that you COULD, w/o worry of burn. The reason you could is because you'll be flushing the old salts from the soil each time you water.

Keeping the fertilizer load always at luxury levels has some drawbacks, so you should try to keep the supply of nutrients at adequacy levels. As long as you are watering so a good amount of water exits the drain at each watering, I would start out with one of these programs: A) Fertilize with a 1/8 strength solution at every watering B) use a 1/4 strength solution every 3rd or fourth time you water C) use a 1/2 strength solution every 2 weeks. Since all my plants are outside in the summer, I sort of use a combination of these programs based on current growth rate, temperature, watering frequency, etc.

". . . do you have to water more frequently in the 1-1-1 mix? How many times a week would you suggest?"

Yes, you'll almost certainly need to water much more frequently than you're used to if you were using a bagged soil. Even though it's very difficult to over-water this soil, you can if you work at it, so do not water on a schedule - water as needed. Different containers will have different intervals between watering.
Until you get used to the soil, I would put a wick in the drain hole. It will drain any perched water if you DO over-water, and it can be very helpful in deciding when you should water. If the wick is wet - wait. Once the roots colonize the whole container, just remove the wick to increase the intervals between watering. Slick, huh?

". . . here's a pic of the dieffenbachia I'm trying to save. I had to butcher it to get rid of the rotting leaves. Do you think it can recover?"

I'll bet on it. ;o) It looks like there is some leaf deformity in it, which looks like a Ca deficiency - prolly caused by the anaerobic root conditions. Plants need a continuous supply of Ca, so anything that interrupts the nutrient stream in a plant can cause a Ca deficiency. You were light on the lime @ 1 tsp per gallon, but if the fertilizer or micro supplement you're using contains Ca and Mg, you'll be fine. Let me know if they are lacking either.

I hope you removed most (all is prolly too much to hope for) ;o) of the soil and trimmed any rotted roots from the diff? The plant will recover much faster if the soil in the container is uniform. If you didn't, I would chop (scissors) the bottom half of the root mass right off & clean the soil off the roots & repot. You can start fertilizing right away - no need to wait.

I don't know if you can tell, but I'm really excited for you. I think you'll never look back. ;o)


    Bookmark   August 30, 2008 at 7:44PM
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When I repotted the dieff I did not cut any of the roots away but i did gently rinse off 99% of the old soil under lukewarm water under the faucet. The roots didnt look to bad to me besides the surprising lack of them. I thought a plant that size would have a big rootball, but not this one. Do you think I should cut them anyway? Also I made a typing mistake about the lime. I added 1 tbsp. not 1 tsp.
And here is the analysis of my fert and micro supplement.

Peters Excel 15-5-15 Cal Mag

total nitrogen- 15%
available phosphate- 5%
soluble potash- 15%
calcium- 5%
magnesium- 2%
boron- 0.015%
copper- 0.007%
iron- 0.075%
manganese- 0.037%
molybdenum- 0.007%
zinc- 0.040%

Bio Genesis Mineral Matrix Micro-Nutrient Supplement 0-0-1

soluble potash- 1.0%
magnesium- 0.5%
sulfur- 3.0%
boron- 0.02%
copper- 0.05%
iron- 2.0%
manganese- 2.0%
molybdenum- 0.0005%
zinc- 3.0%

    Bookmark   August 31, 2008 at 4:32AM
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tapla (mid-MI z5b-6a)

It's hard to tell about the roots w/o seeing them, so I prolly shouldn't offer advice. I would prolly lean toward reducing the roots so they go into the pot in a very tidy and sort of flat arrangement. If I thought the roots would not be able to support the foliage, I would reduce the foliage by cutting the leaves in half across the veins. Later, when the plant has recovered, I would just snip off the butchered leaves.

The butchered leaves make me think of something I encounter frequently. It's just an aside, and not directed toward you, Gary. Some people have certain ends in mind when they grow their plants, and I often need to remind myself that what we expect/want from our plants are different. Some people regard them as decorations, and when they begin to decline, they toss & get something different, or another of the same - the "revolving door attitude." Some equate maximum growth with health. They WANT the plant to grow big as fast as they can push it, but then they often wonder what to do with it. In other forums, I see people that want their potted fruit trees to produce a bumper crop every year - even though the stress can often jeopardize the life of the plant. Anyway, there are other different ways of looking at plants that I don't mention, because my only point was that different people DO have different expectations of their plant material. The reason for bringing that up, was the idea that I would, w/o a second thought, just reduce the roots and cut the leaves in half. ;o)

My way of looking at plant material is to first keep it vital and robust (healthy and growing well), and second - enjoy its appearance; or, I'll gladly sacrifice its appearance temporarily to insure its health. How many people look pretty while in intensive care? ;o) My perception is the greater number of people I talk with on the forums don't look at plant material that way, so when I suggest something like chopping at the roots or cutting the plant back hard to rejuvenate it, they're often aghast & think I'm nutts (2 't's means xtra nutts). ;o)

I think you could shelf the Bio Genesis if you're using the Excel. It really doesn't offer anything your fertilizer doesn't already have, except sulfur (S) and the line between deficiency and toxicity, when it comes to micronutrients, is fine. Since S is often in short supply in container soils, you should probably think about a source. The ratio of Ca:Mg is best at around 4:1. The Excel has it at 2.5:1, so you could still afford to add a little more Ca. Adding a teaspoon of gypsum (calcium sulfate - very inexpensive) per gallon of soil will supply additional Ca AND S. You could also add a teaspoon of elemental/agricultural/garden sulfur to each gallon of soil to cover the S requirement. I just don't think that simply because it supplies S, there is sufficient reason to duplicate the other nutrients by using the Bio Genesis.


    Bookmark   August 31, 2008 at 10:30AM
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tapla (mid-MI z5b-6a)

Gary - to clarify something: You already have lime in the batch of soil you made, so what I said above doesn't apply to that batch - only future mixes that you intend to use the Excel with. You would eliminate the tablespoon of lime from the mix and substitute 1 teaspoon of gypsum in its place. I bet if you look at the analysis of the Excel, most of the N comes from nitrate and not in ammoniacal form. This allows the manufacturer to add Ca and Mg compounds that normally fall (precipitate) out of solution with high % of ammoniacal N. IOW - it's sort of unusual for soluble fertilizers to contain Ca and Mg, so if you're using a fertilizer that contains those elements, you need to tweak the rest of the additives to compensate. Sorry if that makes trouble for you, but once you grasp the concept, it's really easy. ;o)


    Bookmark   August 31, 2008 at 10:44AM
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well I pulled the plant and cut about 1/3 the roots off and repotted in the same soil just top dressed. I watered it and added no additional fert, I fertilized it full strength yesterday. So you are saying in my future mixes to axe the lime and micro-nutrient and add a teaspoon of gypsum per gallon? I have 25 lbs of the excel so I will be using it for a while LOL!! Can gypsum be found at HD or lowes? Here are a few pics of the dieff after I cut it. thanks again Al.

    Bookmark   August 31, 2008 at 4:58PM
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tapla (mid-MI z5b-6a)

"So you are saying in my future mixes to axe the lime and micro-nutrient and add a teaspoon of gypsum per gallon?"

Yes. Because you are using a somewhat unusual soluble fertilizer, in that it contains all the nutrients (except S), including both Ca & Mg, you don't need lime. The ratio of Ca to Mg is ideal at about 4:1, but your fertilizer provides it at 2.5:1. This means that you could stand a little additional Ca. Gypsum contains both Ca and S, so you can kill 2 birds by adding a small amount to your soil, bringing up the Ca ratio AND providing the missing S. Got that? ;o)

"Can gypsum be found at HD or lowes?"

They do sell it, but it might be a seasonal item. If they have it, it will be near the fertilizers in 50 lb bags, which should hold you until somewhere around the time that your great great grand children are just starting to think about a final resting place. Espoma packages it in 5 lb and 38 lb bags. The 5 lb bag of their product will cost almost as much as 50 lbs of generic, but there's prolly something to be said about the blessings of not saddling your great great progeny with the extra 45 lbs.

The roots look great. Put your diff outdoors in full shade that has open sky above (north side of a fence, or building w/no overhang) if you have a spot like that, for quickest recovery.


    Bookmark   August 31, 2008 at 6:02PM
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tapla (mid-MI z5b-6a)

Posted by jillalameda 9 (Sunset 16/17) (My Page) on Sat, Aug 28, 10 at 12:41

(Since the other post had (supposedly) topped out at 150 posts, but Jill was able to sneak an extra in, I had to copy/paste the reply here to answer.)

"If you're still out there, I have a question. Please forgive me if it's answered above; there are well over 100 posts and I only read through the first 20 or 30.
Would adding decomposed granite improve bagged potting mix? If so, what proportion would you recommend?"

It could, if you added enough, but there are a lot of qualifiers that need to be considered. First, it would have to be screened to a size that was in a range from just under 1/8" to around 3/16", and there would need to be a significant fraction of granite. In fact, it would have to be the largest fraction of the soil.

Adding 'some' DG to a heavy soil doesn't change the drainage characteristics of the soil or the height of the PWT. To visualize this, think of how well a pot full of BBs would drain, then think of how poorly a pot full of pudding would drain. Even mixing the pudding and BBs together 1:1 in a third pot yields a mix that retains the drainage characteristics and PWT height of the pudding. It's only after the BBs become the largest fraction of the mix (60-75%) that drainage & PWT height begins to improve; and so it would be if you added the DG.

You cannot add coarse material to fine material and improve drainage & the ht of the PWT. Use the same example as above & replace the pudding with play sand - same results. The benefit in adding DG or perlite to heavy (water-retentive) soils doesn't come from the fact that they drain better. The fine particles simply 'fill in' around the DG or perlite, so drainage & the ht of the PWT remains the same. All the DG or perlite does in heavy soils is occupy space that would otherwise be full of water. The DG or perlite simply reduces the amount of water a soil is capable of holding because it is not internally porous.

If you want to find advantage in a soil that offers superior drainage and aeration, you need to build it into the soil from the start, by ensuring that the soil is primarily comprised of particles much larger than those in peat/compost/coir. The soils I recommend either have a 2/3 fraction of inorganic particles around 1/8" in size (it's no accident this is the size I chose - the PWT is reduced as soil particle size increases, until it disappears entirely as soil particle size reaches just under 1/8"), plus a 1/3 fraction of conifer bark about the same size or a little larger; or they are made beginning with a large fraction of pine bark so drainage and aeration are inherent from the beginning, so we're not trying to amend soils to add these valuable properties as an afterthought.

Getting back to your question directly - You would have to add enough DG of a favorable size so that the DG was about 60-75% of the o/a mix to ensure good drainage and a reduced PWT height. The problem here is, that now you've sacrificed a LOT of your water retention. Better, would be to use half screened Turface or calcined DE (diatomaceous earth) and half of the DG to make up that large fraction(60-75%). This would ensure both drainage and aeration, while increasing water retention to more acceptable levels. Essentially, we're almost talking about the gritty mix here. If you replaced the soil you have with pine bark, it WOULD be the gritty mix.

I would encourage you to try a soil that is durable and based on pine bark, or better still - a soil like the gritty mix. They will make your job easier and likely increase your effort:reward ratio. They also offer a significantly wider margin for grower error, compared to heavier and more water-retentive soils.


    Bookmark   August 28, 2010 at 3:04PM
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Wow! What a fascinating discussion & so much info! This thread is the one that pushed me to join...

So, onto my question: it is now mid-Sept - should I wait until spring to try an airier soil for my houseplants? I think trees grow roots in winter & vegetation in summer, so if house plants are the same (& why wouldn't they be?), it seems to me they'd appreciate an airier soil now... but then I wonder if they'd have a longer recovery in cooler temps & lower light.
I do have about 25' of southern exposure windows, if that makes any difference. My house is also large, old & drafty, with single-pane windows & wood heat. The plants don't live in the same room as the stove, so certainly they're cooler (high 50's to mid 60's) & maybe the air is not quite as dry...

Anyhoo, this summer I potted up a largish, distressed rubber tree from severely hydrophobic soil, a pot-bound dracena pair & a whacked, 1-stem (cutting saved from trash 5 yrs ago) schefflera. I used chunky (screened through 1/2" mesh), mature compost from my pile & as always, filled the bottom 1"-2" of the pots with circus-peanut (y'know, the orange ones) sized rocks for drainage. I did not trim any roots, but was a bit rough with them, so there was some breakage, just not to the extent of a hearty trim. The compost is certainly faster than the previous soil, but surely nothing like your creation.

Should I repot now? And trim roots? Or should I wait? I am in Western Washington, by the way...
Thanks so much for all the excellent information you provide!

PS - I know this post is already pretty long, but I wonder about a soil compromise? The largely inorganic mix you describe, with 1/2" to 1" mature compost atop? Might the small particles filter into the chunks & extend my watering by a day or two? Or, is it just a bad idea...
OK, thanks again!!

    Bookmark   September 16, 2010 at 12:45AM
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tapla (mid-MI z5b-6a)

Hi, GB. Thanks for the nice compliment. I'll touch lightly on several areas. Feel free to respond with questions or comments.

What I write and how I grow comes from the perspective that the most important choice you'll make when establishing a planting is the soil, and the most important property a soil can have is good aeration/drainage for the intended life of the planting, which is why the soils I use are made from particles that either don't break down at all, or break down very slowly.

Some soils are a hodgepodge of ingredients mixed with hope, and others are built as simply as possible around desirable physical characteristics, the ingredients being selected because they contribute to the soil in more than 1 way. That's the type of soil the gritty mix is. Making alterations to it w/o a good understanding of how/why the soil works so well in the first place, and not understanding the impact that particular alterations would have on the soil, will more than likely leave you growing in something closer to what you're trying to get away from, than what you are trying to move toward.

Drainage layers don't improve drainage or reduce the height of the perched water table, but they CAN reduce the volume of water in the perched water table. If you don't understand that phrase, you'll find an even more thorough discussion about container soils if you click on the link.

Now is not a good time to repot tropical or subtropical plants. For fastest recovery and minimal risk of insect infestation/disease due to a weakened plant, repot healthy plants in the month prior to their most robust growth. That would be Jun or Jul for you. You would be best served if you pot up root bound plants into a soil similar to what they are already in, and nurse the plants through the winter by watering carefully & flushing the soil thoroughly several times before summer - unless you have good supplemental lighting, in which case you could get away with repotting now.


    Bookmark   September 16, 2010 at 4:14PM
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thanks for such a prompt reply Al!

I'll leave everyone alone for now...

You mentioned potting into a similar soil; that would be necessary only if the plant were distressed & urgently in need of potting? It's OK to move to a different type of medium if I wait until late spring/early summer?
None of my plants are in such dire straights currently. Except that hylocereus I just inherited from my sister-in-law who moved out of state; it appears to be in ancient standard potting mix - would it be better off staying as-is with light applications of Schultz Instant through the winter?

I think I will try the turface/granite/bark mix. In the meantime, I'll keep (re)reading these soil threads... the idea of making soil with a purpose is very interesting & it's about time it dawned on me :) duh.
I'm not an active fertilizor, so I've always potted the houseplants in soil I thought would feed them. Although, since most of my plants are over 10 years old - some as old as 20 (a begonia, an aloe & a little phil) I can't be too hard on my self for being a late bloomer when it comes to soil! But, as you mentioned in an earlier post, surviving and thriving are not the same...

    Bookmark   September 16, 2010 at 5:20PM
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tapla (mid-MI z5b-6a)

There is no need to feel you're intruding or being a bother, Boots. An open mind and someone who wants to learn makes for rewards running in both directions.

If your plant is obviously in jeopardy of dying over winter because it's horribly root bound, it's better to do something to mitigate the stress. First choice would be to make multiple vertical cuts in the root mass and only pot up into a similar soil temporarily. Second would be a repot, but I wouldn't recommend it unless there was something more than tight roots at work. You can do a full repot, which includes bare-rooting and root pruning (if applicable), next year after the plant(s) have gained some energy reserves.

I would learn how to flush the soil and do it regularly, until you can get your plants into a soil that allows you to water freely enough that salt build-up is not an issue. I'm guessing the fertilizer you're using is 10-15-10. Probably not the best choice for houseplants as your 'go to' fertilizer. No plants use more P than N, so supplying all the extra P just makes it more difficult (than necessary) for plants to absorb water and the nutrients dissolved in water. Excess P can also inhibit uptake of N, Fe, and Mn, as well as other micro-nutrients. It also unnecessarily raises pH. An acid forming fertilizer like MG 24-8-16 or 12-4-8 are better choices. I happen to use Foliage-Pro 9-3-6. It's an excellent choice as your all purpose fertilizer. It also supplies a large fraction of its N in nitrate form, which helps keep your plants from stretching out.

It's not unusual that you don't know anything different than what you've always grown in. Very few hobby growers, other than the few who frequent a few forum sites where the topic is widely discussed, have any idea there are alternatives to bagged, peat-based soils. Hopefully you'll be impressed enough with what you learn and the testimony of others to try something different. If not, at least you'll have learned along the way what issues to watch out for and will have some ideas about what you're seeing and how to deal with them.

Please DON'T be hard on yourself. Make it fun. The more effort you put into growing, the more you get out; but it's still up to you to set the parameters of the 'in' part.


    Bookmark   September 16, 2010 at 11:09PM
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oh! ha-ha-ha! by "everyone" I meant the plants at my house!

Totally off topic:
I did repot the hylocereus today, into a even mix of fine orchid bark, chunky compost, pumice, with some coir... I thought I'd have to break the old pot to get it out! There were random plastic items in the roots, as well as a large chunk of rotty stick & some other junk, so even though I didn't intend to do a total re-pot, it happened anyway. I did pot slightly up, mostly for stability - this is fair sized (still teeny by hylocereus standards, though) and the prior pot was about 4" wide by 8" tall = tippy; new one is the same height, but wider. It also got this plate-sized grow-through thingy on legs I noticed at the hardware store, so the limbs have some support.

Several of the limbs are about 3' long, so hopefully it has what it needs to make it through the winter... a couple broke off, so they are suberizing, then I'll try to root them out. Less "mouths" to feed for winter, but a smaller food factory too. I think it will get to spend the winter in the room with the stove, as it will probably need the extra warmth.

Yes, my fertilizer (once I actually found it! A mouse has apparently gnawed off the top of the dropper bulb) is a 10-15-10... but who knows when the last time I actually fertilized was?

As for peat, I think that was the problem for the poor ficus!! The previous owner left a GIANT bag of it out by the compost bin, so I'm guessing he was really into peat. When I took it out of the pot, the roots were bone dry, even though LOTS of water had run through the pot. It was severely dehydrated due to that old, peaty soil, had dropped all of it's leaves & the ends were even starting to wither. It might get to spend the winter in the room with the stove too, although it is recovering surprisingly well.

Thanks for the encouragement & will be checking out more of the houseplant discussions :)

    Bookmark   September 17, 2010 at 3:03AM
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tapla (mid-MI z5b-6a)

Lol - I can see the meaning of 'everyone' now. ;o) Take care.


    Bookmark   September 17, 2010 at 2:17PM
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Hi Al,
I just wanted to say thanks for starting the Soil Discussion threads and sharing really good information. It really helps us novices.
I've gathered some information based on these threads and found another thread that lists some suppliers here in the Bay Area so hopefully I'll be able to start getting some materials this weekend. Some of my house plants are ready for a split or pot-up and I think I'm ready to use a better mix.
Thanks again!

    Bookmark   March 28, 2011 at 8:49PM
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Welcome forum registration, Thesss. Glad you finally decided to come aboard! :)

    Bookmark   March 28, 2011 at 9:25PM
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Thanks windeaux! :)

    Bookmark   March 28, 2011 at 9:55PM
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tapla (mid-MI z5b-6a)

Hi, Thess. Welcome! .... and you're welcome. If you find you need any help, please don't hesitate to ask.

Thanks for the kind words. ;o)


    Bookmark   March 28, 2011 at 10:02PM
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I am amazed at all I have learned since the inception of this, and other threads on the issue of mediums! I can't thank Al enough for his tireless intervention and contributions, helping me, and scores of other growers to gain the most out of our gardening hobbies!

I'm now ready to amend what I originally wrote, some of which I wouldn't say today. For example, I no longer recommend cocopeat or coco coir products, especially if other medium ingredients are available. Experience has taught me that they're more trouble than they're worth, and that peat is not the finite product that certain sources and industries would have us believe.

Al's articles and written discussions have gone a long way toward putting all the pieces of the growing puzzle together for me, and as a result of applying what I've learned, I'm a much better gardener!

I can hardly believe it's been so long since I first went in search of a better way to grow! This discussion was begun in 2008, and here it is, 2011... my, how time flies when you hold such knowledge and success within your grasp! :-)

    Bookmark   March 29, 2011 at 10:40AM
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Thanks Al! Appreciate the help in advance. I know I'll definitely need some :)

Jodik, I'm glad you posted about Coco Coir products. The feedback on these have somewhat been 50/50. I'll stay away from them :).

    Bookmark   March 29, 2011 at 2:43PM
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In my experience, cocopeat holds way too much moisture for too long a time to be of benefit in a potting mix. I also found that it grew some incredibly colorful molds, such that I've never seen before. Just those two items turned me off to using it. But wait! There's more!

Due to processing methods, coco coir products contain an enormous amount of saline, which needs to be thoroughly rinsed and/or soaked from the product before using. Even the product that claimed to be pre-rinsed required an overnight soak and more rinsing before the water ran clear.

How can a product have a small energy use footprint when it must be processed, and then shipped halfway around the planet to be used by growers? It can't, so it's not as "green" a product as we're led to believe. Peat is harvested in Canada, so its travel to reach us is relatively short.

If all that isn't enough to make a grower think twice about using it, the rate of compaction for cocopeat is incredibly fast! I used it to pot up some bulbs several years ago, and within the space of a few months, the level went from full pot to about half a pot of product. I was not impressed. Upon un-potting those bulbs, I found dead and rotting roots, discolored coir from over-saturation, and the roots that were still live were growing upward toward a source of oxygen.

I simply can't recommend a product with so many negative points.

My experiences were my own fault, though... I neglected to research, and instead took the word of someone without asking why or how it worked. Lesson learned.

    Bookmark   March 30, 2011 at 11:10AM
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Hey everyone,

I had a question about substitutes for the gritty mix ingredients. I am able to get my hands on Repti Bark for the bark fines. I ordered Manna Pro Poultry Grit as the substitute for Gran-i-grit. I've seen in some posts where people used perlite, or that Napa dry oil stuff instead of Turface. Are these good replacements? I searched for Turface through the manufacturers website and there doesn't seem to be a local business that carries it. I know the importance of Turface as the media that will hold most of the moisture content in the soil, so I don't want to replace it with a sub-par media.

Also if anyone has had good results with any other substitutes for the other ingredients, that would be helpful in the future.

    Bookmark   May 1, 2011 at 4:16PM
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tapla (mid-MI z5b-6a)

The calcined DE is an appropriate substitute for Turface MVP/Allsport if you can't find it, and the perlite can be substituted for crushed granite in a pinch, but both substituting either would probably change the ratio of the ingredients slightly. When you decide on what you're going to use, let me know, and I'll suggest a mixing ratio that will approximate the water retention of the basic mix.

What city do you live in - I'll see if there is a nearby source for Turface.


    Bookmark   May 1, 2011 at 5:31PM
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Thanks for the help Al. I live in NYC. I was thinking about making a small batch with left over materials that I have so I can get rid of some clutter before I make a larger batch later with the repti-bark, poultry grit, and turface (or substitute).

I have some orchid bark mix that I will probably have to snap into smaller pieces. That orchid mix also has a small amount of carbon chips mixed in as well. And I also have some perlite that I screened to remove the dust and small particles, but will probably have to screen it again with another screen size to remove more of those smaller pieces.

Oh by the way, What your opinion on the use of repti bark?

    Bookmark   May 1, 2011 at 7:13PM
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tapla (mid-MI z5b-6a)

It's fine, but particle size is important. From what I've read, it comes in 2 different sizes & the smaller size is more appropriate. 1/8 - 1/4" is ideal. See Gary's picture upthread dated Aug 30, 08 - it's perfect.


    Bookmark   May 1, 2011 at 8:02PM
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Sounds good. I will definitely check my local pet store and see if the size is what is need for this mix.

I went back and read a good amount of the original Soil Discussion and saw that you helped someone from the NYC area in the past. Do you know of sourses for all of the ingredients for the gritty mix around the NYC area?

    Bookmark   May 1, 2011 at 11:28PM
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