Need Advice. Gritty Mix (minus bark) and Houseplants

jala4260(10a)April 25, 2012

I have two detailed questions in this thread that I seek advice for. First is to devise proper Turface and Granite Grit ratio to allow for scheduled watering once a week. Second is to find out what to use in my water.

I recently potted most of my houseplants in Al's Gritty Mix of equal parts turface, grit, and bark. However, with the all the houseplants being in-house, the stench of bark (decomposing?) smells really bad!

I would like to switch to using just Turface and Granite Grit. My understanding is that the bark is used to lower pH and provide little nutrients.

I read somewhere on this forum that 1.5 Turface and 1 Grit would equal about the same water retention as 1-1-1 Gritty Mix -- which is the guideline I'm following to devise a varying water retention mixture.

I want to know how to go about with watering -- what to add to my water to compensate for the lack of bark.

I use water from my sink that is filtered (drinking water) with 1/4 Tablespoon of Dyna-Gro Foilage Pro per 1.5 Litter of Water.

Currently, I have lemon/lime trees outdoors giving me plenty of fruits, could I just squeeze the juice from the lemon/limes into my water everytime to compensate (lower the pH) for the lack of bark? How should I do this (how much to use); if not a good idea, what alternatives?

The plants will likely have different pH requirements so they are listed below for reference.

Now to devise a mixture so I can water on schedule for all my plants once a week...

Listed by Common Name --- Botanical/Latin Name -- Gritty Ratio Suggestion

1) Snake Plant --- Sansevieria Trifasciata "Laurentii," "Lillian True," and other var. -- 1.5 Turface: 1 Grit OR 2 Turface: 1 Grit

2) Peace Lily --- Spathiphyllum ... Sweet Pablo and other cultivars --- 3 Turface: 1 Grit or Pure Turface

3) Prayer Plant --- Marantaceae Calathea... --- 3 Turface: 1 Grit or Pure Turface

4) Sago Palm --- Cycas revoluta --- 2 Turface: 1 Grit

5) Lucky Bamboo --- Dracaena sanderiana --- Pure Turface (these seem to grow okay in water?)

I haven't mixed it it -- I'm hoping for some input/corrections/changes to my ratio before I go ahead and do this.

The ones I'm suggesting a high amount of Turface or Pure turface is because they seem to have a high transpiration rate and go droppy quickly in 2-3 days after watering.

I'm currently planting the Peace Lily and Prayer plants in 2 Turface: 1 Grit: 2.5 Bark. They seem go dry fast.

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Some more plants I plan add soon:

6) Norfolk Island Pine -- Araucaria heterophylla --- 2 Turface: 1 Grit or 3 Turface: 1 Grit
7) Pygmy Date Palm --- Phoenix roebelenii --- 2 Turface: 1 Grit
8) Dumb Cane --- Dieffenbachia --- 3 Turface: 1 Grit or Pure Turface
9) Jasmine --- Jasminum sambac --- 2 Turface: 1 Grit or 3 Turface: 1 Grit

I would like to add; the Peace Lily seem to go thirsty quick likely because it was originally root-bound and probably has moss inside of the surrounding roots, which I can't really clean the inside and totally bare-root without damaging or removing many roots. However, the prayer plant was bare-rooted with a fire hose (roots weren't damaged, still intact) and planted in the same Gritty ratio (2:1:2.5) as the Peace Lily. Both can't last a week before getting thirsty.

    Bookmark   April 25, 2012 at 2:31AM
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I wanted to bump this up a bit, because I'm interested in the same question -- specific guidelines (with example formulas) for adjusting the ratio of gritty mix materials for more/less water retention, with specific plants in mind. My big issue is Sansevieria in 4" pots; they seem to do well for a while, then their roots hit some kind of critical mass in colonizing the pot, and suddenly the mix is drying up more quickly than I can water it. Then the roots start dying off and it's all downhill from there. :/

That said... I'm mystified by your problems with the bark. I notice a "wet bark" smell for the first few waterings after I pot something, but it fades pretty quickly, and I've never noticed any particular odor at all from watering after a couple of weeks. Looking over what you've written above, though... I wonder if maybe you're overfertilizing, and that's triggering some kind of decomposition process? The label instructions for Foliage Pro 9-3-6 are for 1/4 *teaspoon* per gallon, which would translate to... about 1/12 tablespoon per 3.75 liters, maybe 1/16 tablespoon depending on whether you're using metric or UK. So you're fertilizing at least six times the recommended rate, unless you misspoke in your original description...

Here is a link that might be useful: Foliage Pro 9-3-6 Application Rates

    Bookmark   April 25, 2012 at 6:03PM
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Correction on my original post.

I use 1/4 teaspoon of Foliage Pro per 1.5 Litter( = 0.40 gallons) of Water

The instructions for my Foliage Pro were as follows for handwatering. 1 teaspoon per gallon weekly or 2 teaspoon per gallon every 2 to 4 weeks. So based on that, my fertilizer strength is low.

I've read somewhere where Al said he waters his Gritty Mix plants with foliage pro weekly at full strength. I assume it's because the medium drains so fast and doesn't have much nutrients as it's inorganic.

    Bookmark   April 25, 2012 at 6:56PM
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I grow in barkless gritty mix, in basically 2 different ratios. For succulents and "dry" plants, I use a 1:1 turface to grit ratio. For tropical type plants, I use a 2:1 turface to grit ratio. I find that if you use ALL turface, it stays wet too long, and I'd recommend against it.

Now, as for watering once a week, well, it'll be impossible to achieve this, because sticking to a schedule won't provide optimum growing conditions. Plants need to be watered when they need water, not on "watering day". It'd be like you being given a bottle of water to drink every 4 hours. Sure, thats great when you're sitting on your duff watching TV, but what about if you're outside in summer, sweating your butt off? You'll dehydrate unless you get water more frequently. Plants are the same, in that they consume water differently at different times, and you'll need to recognize that and provide water when needed. Also, pot size and root fill will change watering needs, as will temperature, humidity, time of season, and other things like having a cieling fan blowing around the air, causing increased transpiration.

As for your water pH, the bark doesn't have much effect at all in the gritty mix, so you're best off to make sure your watering solution is up to snuff. I use 100% rain water, which naturally has a low pH, so I am set on that. If you use tap water, odds are the pH is quite high, and to lower it, you'll be better off with vinegar added to the water. I'm not 100% sure on the amount to use, so you'll have to research that.

As for your plants going droopy, I'm going to suggest you verify that when you water, that you do so thoroughly. What I am getting at, is that with gritty mix, especially with hydrophobic pine bark, just dumping water in doesn't give you thorough wetting. Next time you water, scratch down an inch or so, and you may find that the mix is bone dry. I was having that problem, and found it due to my use of clear containers for rooting cuttings. Clear containers let me see the roots, so I can tell when they are ready for a normal pot. However, when I started with gritty mix, I noticed that only the top and bottom were wetting, and the middle was staying dry. I now use a turkey baster to reapply the water from the catch tray, until all of the mix is wet. This problem was drastically reduced when I moved to a barkless mix, but I still do have to reapply water to ensure thorough watering. This is likely the source of your wilting problem, but if you rough up the plant roots when you remove the old soil in preparation for gritty mix, you may have some problems with water uptake from damaged feeder roots. Check it out and see what you find, because I bet it's the dry mix problem.


    Bookmark   April 25, 2012 at 6:56PM
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Oh, I use FP 9-3-6, and I use roughly 1tsp per gallon during the growing season, at every watering, and 1/2 tsp per gallon in the off-season. You'll need to fertilize at every watering, as your gritty mix doesn't hold much, if any, nutrients, especially without the bark.


    Bookmark   April 25, 2012 at 7:02PM
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As for watering on a schedule, I got that idea from Al as I remember reading a post where he said he does that to simplify things and that it's almost impossible to overwater with Gritty Mix.

As for rain water, that is not a reliable source. I didn't want to add vinegar as my original problem was the smell and vinegar is strong as well. What about the lemon, the smell is more acceptable, is it a good source to adjust the pH of my tap filtered water?

My plants are indoors inside my room, which is sealed from all other areas of the house. Thus, there not much air flow, humidity changes, etc that would affect my soil drying at different rates at different tiems hence I wanted to water on schedule.

I went overboard on some Sansevierias, acquired some 5 feet Laurentii which rhizomes were so big I had to get a 17 inch pot to fit them in. With Gritty Mix, that container must weight over a 100 pounds. This one is a pain to water -- It's a 17 inch "self-watering" pot which has a saucer/water reservoir where the water drains into (or you add water to) and I use a turkey blaster to suck and toss out the excess water. It's a painstaking task that takes 20+ minutes to completely water that pot as I have to suck out the excess water before I can water again (or it overflows into my floor). It's too heavy to take the saucer out and dump the water if you were wondering. That's why I need devise a mixture to water once a week which I figured is the best compromise.

    Bookmark   April 25, 2012 at 7:10PM
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I believe Al has hundreds of plants, so simplifying things is more economical for him. I only have 3 outdoor bonsai, and 17 indoor plants, half succulent, half tropical, so I water based on need, not time. You CAN use lemon juice to lower the pH, but how much I do not know.

For rain water, I have a custom delux collection system that results in a 55g barrel, in my basement, that can be filled in a decent rain or two. Rain water is tops for watering, hands down. But, if you must use tap water, then so be it; use the lemon juice to bring down the pH. You may need a kit to check it though, because you shouldn't be going into it blind. You'll want to know what your starting pH is, and how much lemon juice to add to get the pH where you want it. They do make a product for lowering pH too, which is cheaper than lemon juice, unless of course you have lemons sitting around.

As for the Sans, I feel your pain, as I have a large one in an 18" pot, with gritty mix. It is seriously heavy, and in fact never moves. I just water it, and as you do, remove the waste water with a baster when I'm done. I also have a yew bonsai in a large pot outside on the deck that kicks my ace when I have to move it, or lift it into a saucer for watering.


    Bookmark   April 25, 2012 at 10:47PM
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Still looking for help for my original two questions regarding lowering pH and Turface:Grit ratio for individual plants. I use tap filtered water so I assume the pH of the Turface will rise above 7 at some point (most of my plants prefer below 7).


    Bookmark   April 26, 2012 at 12:21PM
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penfold2(4b, MN)

I really doubt the smell is coming from the bark. Conifer bark decomposes very slowly and should only have a nice fresh smell. If you smell something bad, it is most likely decomposing roots, or something else that was added to the soil. If the plants remain healthy and growing, and no organics are being added to the soil, the smell should disappear.

Also, vinegar will have no noticeable smell when diluted in water, so there's no reason to avoid it. It's a lot easier than squeezing lemons. You should get a pH test kit and see how much it takes to reduce the pH to around 5-6 and then use that much from now on. Otherwise you're just guessing. If you can get a water report that lists alkalinity, you may also be able to calculate a reasonably accurate dosage. Testing will always be the best method, though.


    Bookmark   April 26, 2012 at 2:46PM
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It does seem unusual to have offensive odor coming from bark...something's amiss there?

I also copied/pasted a section of a post from Al on the ph issue, he had written that he, too, grew some plants without the bark...Sorry that I don't know how to link the post to this's from 2009. I'm pretty sure the first sentence should say "the ph of the media is a consideration"

" - the media of the pH is a consideration in container culture, but it's not vital. The soil solution pH is more important. My water pH varies by season, but in summer it's usually between 8.0 - 8.5. I don't do anything to it to lower the pH and my plants fare very well. In winter, I have noticed some minor yellowing in new growth on things under lights, and have used a tablespoon of vinegar per gallon of water each time I water to neutralize some of the alkalinity in my tap water. It usually clears it (probably a pH induces Fe deficiency) up quickly. "

If you want, you could consider testing the ph of your water to see how much vinegar you need to add, the ph near where you'd like it to be...

    Bookmark   April 26, 2012 at 5:04PM
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RE: Question for tapla - 100% turface mixtures
Posted by tapla z5b-6a MI (My Page) on Thu, Feb 26, 09 at 20:47

This is the citing for the above cut/paste. The thread seems to address your quetstions, and it's interesting reading...

    Bookmark   April 26, 2012 at 5:18PM
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Jala, I gave you my opinion of the turface to grit ratio, which is based on my experience. I don't think each plant needs a different ratio, but rather the type of plant in regards to watering. If it's a succulent or other "dry plant", 1:1. If it's a tropical or "moist plant", 2:1 turface to grit, respectively. Thats how I do it, and have been quite successful. The good thing is, you can adjust your ratios to suite, so if you feel you need more moisture, increase the turface. If you need less, then increase the grit. You have to jump in and get your feet wet, and gain some experience. You're not going to get an answer from one person, and then an Amen from everyone else on that answer. People have different methods, and different constraints when it comes to watering and such, so what works for one, may not work for another.

I'll add that of the plants you listed, I only have the snake plant, which I grow in 1:1, as it is a succulent and likes to dry out. I also have a lucky bamboo, which I grow in a 2:1 (T:G) mix, and it has been doing great. The bamboo has been with me since 1999, when it was growing in the famous vase of pebbles and water. It never thrived until it was taken out of the water. I suspect that you could go 3:1, but I still wouldn't recommend ALL turface, as it stays wet too long.


    Bookmark   April 26, 2012 at 5:23PM
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Jala - Ah, that makes *much* more sense for fertilizer amounts. :) Re vinegar vs. lemon juice, I don't use either of them, but lemon juice tends to be a bit more acidic than white vinegar, so I'd theorize you'd use a bit less... If you're really worried about odors, though, you might check a hydroponics store for what they call "pH Down". Depending on the brand, it's highly concentrated citric or phosphoric acid; you'd need to be a bit careful with it (don't get the concentrated stuff on your skin!) but the non-organic forms are completely odorless and keep indefinitely. It might look expensive at first (I paid around $15 for a quart), but you don't use much at a time (1/8 tsp per gallon drops me to around 5.5) so it'll last you a long time... Longer than an equivalent volume of vinegar or lemon juice, since both of those eventually go bad. You will need to invest in a pH testing kit to measure how much acid you need to add, though. (Which isn't too bad... You can get a small pack of full-range pH testing strips from Hong Kong for $2 or less on eBay, shipping included.) Note, if you don't fertilize at every watering, you should check pH with and without fertilizer -- you may need to add different amounts of acid depending on your fertilizer status.

Joe - Thanks for the info! So you can get away with 1:1 for Sans? I'll have to experiment with this next time I see Sans on sale at Home Depot... Put one in "classic" gritty mix, one in 1:1 turface:grit, and one in hydroculture, just to see which one does better in my conditions.

    Bookmark   April 26, 2012 at 6:26PM
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dickiefickle(5B Dousman,Wi.)

As for watering on a schedule, I got that idea from Al as I remember reading a post where he said he does that to simplify things and that it's almost impossible to overwater with Gritty Mix.
You may need to re read ,sometimes we read things that arent there
plants need to be watered on their schedule ,not yours

    Bookmark   April 27, 2012 at 2:52AM
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