Gritty Mix Questions for Al

gtw7983February 3, 2011

Hi Al, I've been studying your gritty mix for a long time and finally starting making it now. During the process, I have several questions still not sure about. I'd extremely appreciate it if you could help me out.

1. Just to confirm, the best size for the pine barks is between 1/4" to 1/8"; for granite grit is the1/8".

2. I live in a area with very hot summer (highs in the 100s), so what do you think is the lowest percentage of granite I can use on the mix?

3. I use the gritty mix for mostly tropical fruit trees. I read from your previous posts that for trees with leaves, I can't barefoot it when repot. My concern is if the peat based soil around the roots will cause disparity in the new container in terms of water retention. What is your advice on barerooting oe not for tropical fruit trees.

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tapla (mid-MI z5b-6a)

1) Yes - if using pine bark instead of fir bark (they're shaped differently) you can use 1/8-3/8 with no problem. If you can find the granite or cherrystone, get grower size or #2 size, which will be about 1/8" to a little larger.

2) Why not try
4 screened Turface
3 screened bark
2 granite.
That will hold a LOT more water than 1:1:1

3) Early spring. Probably now, for you - or very soon. Don't bare-root entirely. Bare root about half the tree in pie shaped wedges. Complete the project next spring. After that, it will be easier (the gritty mix makes repotting MUCH easier) and you can extend the intervals to maybe every 3 years. Because the gritty mix holds little or nothing in the way of perched water, you can pot in a much larger container than would be advisable if you were using a heavier peat/compost-based soil. Still, with the extra Turface, it would be wise to employ a wick until the plant is well established in the container.

I did a presentation for a Master Gardener's group last week, and a wick I had taken no notice of that was hanging from the bottom of one of the potted plants I took, started a very enthusiastic conversation about soils/drainage that lead to an invitation for another talk and and a presentation to the public at some shindig they're having in Jun. Most growers get very enthusiastic and the questions fly when someone shows them something with the potential to improve their effort:reward quotient.

Best luck!


    Bookmark   February 3, 2011 at 9:30AM
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Thank you so much for your response Al!!!
What does the wick look like? Where could I find one and how would I install it?
Sorry for so many questions. Thank you very much for your help!
Hope everybody has a great day!

    Bookmark   February 3, 2011 at 11:32AM
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tapla (mid-MI z5b-6a)

You can use lots of things for a wick intended to help a pot 'drain', but if you are using it to water (not suggested unless you're using it as back up while you're away) it needs to be quite absorbent. I use strands from a 100% rayon mop. I bought a mop head from Ace Hdwe a couple of years ago for a few bucks & I still have half of it left (and I do more than 150 repots each year - but I don't use a wick in all of them.) Man-made chamois is also 100% rayon & can be cut in strips with a pair of scissors. That also works quite well. Here's a picture of how I set it up, though you don't need to wind the wick around the inside of the pot like I did.

Leave the wick dangle below the pot 2-3" after you water. It will pull any extra water from the soil when the planting is immature. After the planting has grown & roots colonized the entire pot, just yank the wick out and you get the extra water retention as you need it.

Plants do best when the colloidal surfaces are just damp, with a very thin coating of water on the surfaces - not wet or soggy. Excess water between particles deprives roots of O2 and inhibits root function/metabolism. We make a judgment or compromise when we choose what kind of soil we grow in. On one hand, we can choose a soil that always has good air porosity between the particles and water more frequently. These types of soils offer the best opportunity for plants to grow to their potential. If we want convenience, and have our priorities arranged so we're left with little extra time to devote to our plants, or we just don't feel like watering more often, we then choose a soil that offers more water retention; but that water retention comes at the price of reduced aeration - it can't go both ways.

The gritty mix is kind of unique in that it holds good amounts of water in the internal pores of the absorbent materials - the Turface (or DE) and the bark. This means that the space between particles is always well aerated, which is very important to maximizing root health.

At first, it seems like a lot of work, but once you're set up to screen the Turface & bark, and you've located your sources for materials, there's nothing to making it. I screen bushels of Turface ahead of time. I'm lucky in that I have a source for pre-screened fir bark in 1/8-1/4", and granite I get within 1-1/2 miles of home. The Turface I can get within 2 miles of my business. I can easily make a bushel of soil in 15 minutes after the screening is done.

Here's the wick:

Once you decide what you're going to fertilize with, we should talk again. Unless you're not done now. ;o)


    Bookmark   February 3, 2011 at 2:08PM
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I hope this is a good place to ask a question. When you screen turface and NAPA/Carquest DE, which product ends up with more usuable material for grit mix?

I read somewhere that either DE or turface has a lot of fines but just wondering which one has the least fines?


    Bookmark   February 3, 2011 at 9:21PM
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tapla (mid-MI z5b-6a)

The size of the Turface can vary somewhat from bag to bag, but you should end up with about 70-80% usable material. The calcined DE varies considerably by manufacturer/packager, so it's hard to say.

I looked up a thread I remembered that discussed the thought that the CarQuest DE was a little larger & more uniform in size. You can look for yourself (link below) and see what you think. If you decide on one of the DE products, freeze it in water overnight to be sure it's stable before you make a big batch of soil.


Here is a link that might be useful: Turface substitutes

    Bookmark   February 3, 2011 at 9:39PM
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Just read the Turface link you posted above. Sometimes theres too much detail and conflicting info on this stuff. One poster says the Carquest DE held up find after soaking and freezing, and another said it turned soft after soaking.

I guess you can't really tell before buying, you just have to test each bag before you make soil with it...

    Bookmark   February 3, 2011 at 10:15PM
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tapla (mid-MI z5b-6a)

I'd definitely be interested in looking at the larger (particle size) product. I'll watch for a Carquest store & pick up a bag if I see one (I don't pay much attention to where the parts stores are located). If you buy a bag, let me know how you fare, and I'll do the same. Deal? ;o)


    Bookmark   February 3, 2011 at 10:24PM
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Thanks Al. I called the nearest Carquest and they have many different kinds of floor drying materials. I'll have to stop in next time I'm there and actually look at the bags.

    Bookmark   February 4, 2011 at 10:09AM
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tapla (mid-MI z5b-6a)

I THINK the post I linked to had some part #s, so at least you have a starting point.

Later. ;o)


    Bookmark   February 4, 2011 at 2:41PM
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Yes... I believe it's a specific part number you'll be looking for... not all floor dry items are created equally.

Part #8822 from NAPA is what you're looking for.

Margo, I'm linking to a very interesting site on bonsai and bonsai soils... it's got loads of great information, and is highly interesting, I think. It falls sort of in line with what we're talking about, and it pictures items like the NAPA floor dry and other substitutions a person might use. The site is in the UK, but they do cover some items we'd find here, in the USA.

Here is a link that might be useful: Cat Litter, Floor Dry, and Other Soil Componants...

    Bookmark   February 4, 2011 at 4:05PM
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Al, yes there is a specific part number at CarQuest. I had to run an errand so I stopped in there today. Turns out the local CarQuest doesnt stock that particular type of DE, and they have to order it. Might be about a week the guy said. They had lots of types of oil dry but I didnt want to try that as I've read a few bad things about it not holding up.

Thanks for the link Jodi, I'll have a look!

    Bookmark   February 4, 2011 at 4:47PM
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My pleasure, Margo. I stumbled on it when I was looking at different bonsai soils and their components. There's great soil info there, but also, do take a few minutes and check out the tree photos the grower has... they're so awesome! :-)

They remind me of some of Al's bonsai trees! It really is a true art form!

    Bookmark   February 4, 2011 at 11:48PM
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Thanks Jodi. Interesting reading. I'm concerned that several bonsai sites and so forth recommend cat litter, oil dri, and others as a turface replacement, but in most cases there are conflicting results. Hmmm...

I guess you just have to either stick with turface or do a lot of experimenting before using! I th ink I'll try and stick with turface.

Jodi, do you use turface or some other similar product?


    Bookmark   February 6, 2011 at 8:47AM
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The mix I use consists of ReptiBark, Manna Pro poultry grit granite chips, perlite, and turface. I use it for my indoor plants and bulbs.

If I can't get my hands on turface, I would go for the NAPA floor dry.

Most cat litters and floor dry items will list on the bag what the ingredient is... and some will even list what the product can be used for, and in some cases, that includes plant medium. From what I gather, we're looking for calcined clay or diatomaceous earth. The bonsai site is a gold mine of information, just by showing us other items we could look into.

Like anything else, we have to research a bit and take it all with a grain of salt and a little logical thought. There are bound to be controversial writings at each website. The bonsai website I linked is actually in the UK, so the items he lists will be more available in Europe. But there are a few lines written about what you can use in America. I think he points more toward NAPA floor dry in the US.

Also, he shows how to test items... like by freezing overnight and such... to see how they hold up. I like the website because it gives me ideas. It makes me think. If I couldn't locate turface or NAPA oil dry, what would I look for? I'd probably begin in the cat litter aisle at PetSmart or other large store, or I'd look for pumice. The possibilities out there is really what the bonsai website is about.

Personally, I would stick with turface if at all possible, and go for the NAPA floor dry if turface is unavailable.

    Bookmark   February 7, 2011 at 8:24AM
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I think you are right on this. When Al suggests using Turface I'm sure that's the best material to use in the grit mix. I will plan to use Turface and only use the NAPA Floor Dry as a backup if I can't find Turface. All the other cat litter and dry products seem to have unpredictable results. One person says they work perfectly while another says they break down after soaking or freezing. Too much guesswork for my taste. I dont have a lot of spare time or money to buy bags of ingredients and run experiments so if a product has been tested and is available in my area, why not use it? :)

So Turface it is. There is a John Deere place about 20 miles from here so that's a good place to look. They can probably order it if they don't stock it.


    Bookmark   February 7, 2011 at 2:13PM
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Turface really is the best material. Unfortunately, not everyone can get their hands on it, so it's good to know about alternatives. But turface is what pretty much everyone in the States uses... that, or the NAPA oil dry.

I think they have stricter regulations on things in Europe, so the cat litters found there would not be overdone with chemicals, as they tend to be here.

Anyway... the bonsai website was interesting reading for me, and it kind of reinforced the concept of the gritty mixes... and it made me think about the various ingredients and their sizes, and what I could possibly substitute in case I couldn't locate something. Luckily, I was able to come with what I needed.

Yes, any John Deere dealership should be able to order it if they don't already have it. Good luck, Margo! I hope they have it in stock for you!

    Bookmark   February 8, 2011 at 9:22AM
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