Jumping into the abyss ... part 1

terratoma(7a)April 11, 2013

Thanks to Al and others in the recent past, I learned about overwintering recently purchased Japanese maples, 5-1-1 mix, root pruning and much more. I've decided to take the plunge with the Gritty Mix and have a few questions. (And while I'm making a mountain out of a molehill ... if the molehill is important, perhaps that somewhat justifies the mountain.)
Have scoured the mountains around here and failed to find 3/8" hardware cloth for screening purposes; and I'm not inclined to order it online (50' minimum order + shipping!) Am wondering if the following uses of the hardware cloth I do have (1/2", 1/4", 1/8" and insect screen ... 1/16", I assume) ... would work:
Gritty Mix
1. Instead of the recommended "whatever pine bark that passes through 3/8" but not through 1/8", can I use 1/2" and 1/8", respectively?
2. Instead of the recommended "whatever Turface passes through 3/16" but not through 3/32", can I substitute 1/4" and 1/16", respectively?
More to come ...

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nil13(z21 L.A., CA (Mt. Washington))

i dont use 3/8" screen andI think a lot of people have had the same problem you are having. I use 1/2". It's not ideal but it works.

    Bookmark   April 11, 2013 at 3:53PM
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Thanks nil13.
I've searched and read (and re-read, and re-read again) every post under a search for "screening gritty mix". While there is no 100% agreement, I've noticed a gradual shift/modification in the screening dimensions. Many suggest screening Turface only over insect screening (1/16") and don't first screen out anything larger Also, there are many who suggest using 1/4" and 1/8" for the pine bark fines.
I suppose I'm making a big deal out of this, but I want to make an effort to get it right the first time around.
Any thoughts?

    Bookmark   April 24, 2013 at 5:28AM
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dsb22(z7 VA)

Hi, I just made my first batch of Gritty Mix last week. I bought Pine Bark Fines that looked as much as possible like Reptibark to begin with and then only screened through 1/2". I screened the Turface through insect screen. Only rinsed the Gran-i-grit.

I've had three small Japanese maples in the mix for about 5 days. With the first tree, I don't think I had the mix wet enough before putting the tree in the pot. It initially wilted and I've had to water it a couple more times. It seems okay now and the other two trees are doing well. The mix seems to drain very quickly. For my JMs, given the hot summers here and limits on the time I have to water, it seems to me that I wouldn't want my mix to drain even faster by screening out smaller particles of bark.


    Bookmark   April 24, 2013 at 10:03AM
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tapla (mid-MI z5b-6a)

One feature I value about the gritty mix is, you can adjust the water retention w/o introducing small particles that ensure a perched water table. In order to get everything you can from the gritty mix, it needs to be screened to eliminate a PWT. If you want more water retention, simply increase the amount of Turface and decrease the amount of granite commensurately, or add an equal fraction of screened calcined DE to the mix:
1 bark
1 Turface
1 calcined DE
1 grit

You CAN do whatever you wish, but my goal was to choose particles as small as possible w/o them being so small that a PWT was created. Anything larger is simply overkill and of little benefit. I like the bark a little larger than the inorganic fractions because the added size provides a buffer against size change as (unlike the inorganic fractions) the particles of bark break down.


    Bookmark   April 24, 2013 at 4:34PM
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dsb22(z7 VA)


That makes sense. Thank you for replying. I bet that information is in multiple old posts too. And I've read hundreds but somehow I missed it. (What do we have to do to get Gardenweb to give this forum a FAQ?!) I've been debating whether to put my big JMs into the Gritty mix vs the 5-1-1. I have another small JM to repot tomorrow--I don't think I have the right kind of diatomaceous earth on hand so I'll increase the Turface and decrease the granite with that one.


This post was edited by dsb22 on Wed, Apr 24, 13 at 20:42

    Bookmark   April 24, 2013 at 8:37PM
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Hi Deanna and Al
I have five Japanese maples ready to place in containers and, while initially thinking in terms of the 5-1-1 mix, I decided to jump in with both feet to Al's Gritty Mix. Searched all the posts about Repti Bark because it seemed to be the favorite of many posters. Some indicated that they could use it straight from the bag, although some said the bark in the larger bag (24 quart) seemed a bit large and might need screening.
I bought a four quart and an eight quart bag yesterday and decided to screen the bark, using 1/4" hardware cloth, just to satisfy myself. (Actually it was a ten quart bag; PetSmart offers a special of ten quarts for the price of eight.) Results were a bit of a mystery. Only 1 3/4 quarts of the four quart bag passed through the 1/4" screen, leaving 2 1/4 quarts as too large. Of the ten quart bag, only 4 1/2 quarts passed through the 1/4" screen, leaving 5 1/2 quarts as waste. I was naturally expecting a much larger percentage to pass through the 1/4" screen. So ... I've goofed somewhere along the line. Am I mistaken about the 1/4" - 1/8" parameters of the fir bark? (FWIW, all those large pieces did pass through a 1/2" screen.) Al, you mentioned earlier in this thread that you liked the bark a little larger than the granite and Turface. I'm planning on using Gran-I-Grit at 1/4" - 1/8" and Turface at 1/4" - 1/16". Would the Repti Bark I bought, over half of which is larger than 1/4" but less than 1/2", be too large? If so, I don't mind going back to the less expensive pine bark. (If over half of the Repti Bark can't be used because of size, that's a mite too expensive)
BTW, are the screen sizes I listed for the grit and Turface ok? The Turface seems a bit small at 1/16" but I believe I read that too much was wasted if you limited the size to 1/8".

    Bookmark   April 25, 2013 at 4:57PM
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tapla (mid-MI z5b-6a)

D - I volunteered to handle the FAQs for this forum after they had announced they were looking for an editor(?), but didn't hear anything from admin after the offer. In fairness, it WAS during a period of strife that centered around purposeful dissemination of misinformation, and involved several forums, but the issue was resolved as soon as the antagonists were removed.

I have a good friend in VA who uses the gritty mix in a 1:1:1 ratio (same mix I use) for all her trees, so you really don't need to be too concerned about going after the added water retention - at least as far as plant health goes.

G - if you use grower size Gran-I-Grit, you have the right size. You can use the larger bark in a pinch, but 1/8-1/4 in fir is best - a little larger is ok in pine because the pieces are flat. We accept that Turface screened over insect screen is just a little on the small side, but use it so we don't lose so much. Finding a screen between 1/16 & 1/8 would also be a problem for most if there was something slightly bigger. I just wish the particle size for Turface averaged about 1/16 larger.


    Bookmark   April 25, 2013 at 5:23PM
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I appreciate the advice. I'll use 1/4"-1/8" fir bark (will screen Repti Bark) at least for the five Japanese maples I have. I'm not a glutton for punishment, but can you see a problem if I screen the Turface and Gran-I-Grit (am using grower size) so that they are also 1/4"-1/8"? (I'm not concerned about losing so much Turface by screening it at 1/8"_ it's not that pricey around here _ and only one-third of the grit is lost through the 1/8" screening). Or should I simply screen them both at 1/16"?
I'd like to try my hand with additional plants after the maples are in containers. Unfortunately, the Repti Bark is pricey, so I'll have to begin using it right out of the bag, where 60-70% is larger than 1/4". Given the increase in the size of the bark, what adjustments in particle size should be made, if any, to the Turface and grit?

    Bookmark   May 1, 2013 at 4:15PM
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