Try reading the thread at the link below. I maintain some 2-300 woody plants in containers at the moment, and I've been at it for around 20 years. That isn't to say they come and go, like a nursery ..... I maintain the SAME group of plants year after year, so I've learned a little about keeping them continually in fine fettle. ;o)

Al

Here is a link that might be useful: Trees (and other woody stuff) in Containers

Thanks! I'm a beginner so trying to absorb all of this.

Sounds like I should do a mixture of turface, granite and pine bark.

I own a bag of permatill. Is that the same as granite?

And should I sift my fine pine bark mulch before using it?

The Permatill is similar to Haydite or pumice. The answer to whether or not it's a good idea to use it in the soil is its size. If it's BB-size to BB-size X2 it's ok to use. If you use it in place of granite though, you'll probably want to increase the amount of permatill you use and decrease the amount of Turface.

If you decide to make the gritty mix, you should screen the fines out of the bark and use pieces that are about 1/8-1/4" if the bark is chunky and 1/8-3/8" if it's flat & flaky.

Al

Thank you so much for your replies! I have enjoyed searching your name with various keywords. Very informative! I do have a few more questions though...

I checked my permatill bag and I can't find anything about it's BB-size, though I did figure out it is slate and to prevent voles. If it helps, here is link to the kind I have: http://www.comforthouse.com/215297.html?feed=ysw

Now, if I don't sift the pine bark fines out, does that just shorten the life of the pot?

Another question I have is whether this mix of pine bark, granite and turface is - is it suitable to growing all plants?

I want to put filler into the tree pots and don't want to make the mistake of putting something in the pot with it that can't handle this gritty mix. I have a large variety of shade plants for my zone. A couple things I'm considering are Autumn Joy Sedum, Alyssum and Caladiums.

Also, I have recently figured out I have a HUGE squirrel problem. They are digging up everything in the few pots I have outside now. I read that they 'smell' freshly potted soil. Will the gritty mix deter the squirrels since it's kind of soil-less?

My current solution was to put lava rocks as mulch in the pots. But for one of the pots, the squirrel just ripped up the plant directly to avoid the rocks, which tore off the roots of my ebony knight mondo grass. :-(

I haven't been able to locate 'Gran-i-grit', but I did find 'Manna Pro Poultry Grit'. They are equivalent, correct?

When I do measure this all out, is 1:1:1 a volume thing? Like, I put one scoop of each of them and that becomes the right amount?

If you screen out the fines of pine bark, do you have another use for the fines?

I also have read about insect problems with the little buggers going up the holes in the bottom of the pot and to use insect screens before putting everything in the container. Is this needed for the gritty mix also?

All I can say about the PermaTill is that it comes in various sizes, and the size that would be best for making a mix similar to the gritty mix would be between 1/2 BB-size to BB-size.

"Now, if I don't sift the pine bark fines out, does that just shorten the life of the pot?"

If you're making the gritty mix and you don't sift the bark, or you use a product with a lot of fines, you sort of negate the whole purpose of making it. It's structural longevity and high degree of aeration are its hallmarks. If you start adding fine particulates to it, you might as well opt for the 5:1:1 mix or similar, because there would be little advantage in a gritty mix with lots of fines in it over any other soil heavy on fines.

"Another question I have is whether this mix of pine bark, granite and turface is - is it suitable to growing all plants?"

I have yet to try a plant in it that hasn't done extremely well. I don't use it for short term plantings like veggies and flowery display containers, but I use it for everything that might be in the same soil for more than a single growth cycle - all my woody plants and houseplants, including cacti and succulents are in it.

Filler

Use whatever you want as a filler. Empty or water-filled soda bottles work well. A properly made gritty mix holds no (or VERY little) perched water, so there is no worry about water perching above material used as a filler.

Squirrels

The gritty mix won't deter them. I probably found 30 black walnuts buried in the pots of material I'm growing on for bonsai that I've repotted so far this spring. You'll need to find an alternate method of dissuading them.

Gran-I-Grit is actually mined by the NC Granite Corp in Mount Airy, so it shouldn't be too hard to find there. If Manna Pro is all granite and the right size, there's no reason it can't be substituted for Gran-I-Grit.

The mix is 1:1:1 by volume, then a tbsp of gypsum/gallon of mix.

The bark I use is pre-screened, but if I had fines, I would use them in the 5:1:1 mix, spread them on the garden or beds, add them to the compost pile, or use them in hypertufa projects. I always use either insect screen over the drain holes or plastic canvas, which is an inexpensive plastic mesh that comes in 9x12 sheets, available at most hobby stores in the needlepoint section. Paste this to your browser to see what I'm talking about: http://bagntell.files.wordpress.com/2009/12/pcanvas2.jpg

Al

Thanks Al!

I located and bought some turface and pine bark. I called about 4 or 5 places and finally located the Gran-I-Grit. I arrived today at the place to buy it only to find out that some other guy has been buying out ever 50 lb. bag of it right off the truck - and he is using it for your gritty mix receipe too! I will go back tomorrow when they get another shipment in.

I also bought Osmocote Plus. Hopefully this works in place of Micromax? Or do I not need that for these tree containers?

When I spoke of filler, I actually was referring to filler plants, like in thriller, filler, spiller container potting. But since you brought up fillers in the bottom of the container, that brings me to a new question. Can I put green bean cans in the bottom? Or will those rust and do bad things to the soil & plants? I have large GB cans that seem so much more sturdy than plastic bottles but don't want to cause issues.

I've read on other threads you've written that you use either gypsum or garden lime. How do I know which one to use? I went ahead and bought both, figuring I'll use them at some point. (I'm trying to amend my in ground top soil - very hard clay - so I'm sure it'll be good for something.)

Oh & I'm still confused about 'BB-size'. Are you talking about like bullets for BB guns maybe?

And thanks for mentioning hypertufa - I had never heard of it. After googling it, it looks like another whole world of fun to explore!!

Mj - Who'd'a thought there'd be a run on crushed granite? ;o)

You should be just fine with the Osmocote Plus.

Laughing about the 'filler' thing. I use all kinds of different plants for fillers - a wide variety.

I would use something that soil can't get into for ballast in container bottoms. Soda or milk containers with the lids screwed tight work well. I suppose you could use GB cans turned upside down if you wanted to. ;o)

The basics are: Use lime in the 5:1:1 mix and gypsum in the gritty mix. When you use gypsum, use Epsom salts every time you fertilize at 1/4 - 1/2 tsp/gallon.

Yes - BBs - like bullets for BB guns - baby ball bearings about 1/8" in diameter to 1/2 that size. ;o)

Al

Hmm... So plants are supposed to grow in this and like it?

{{gwi:19339}}

I actually kinda think I messed up since the pine bark looks large to me. It was the smallest I could find ('mini nuggets') short of buying the fines called 'conditioner'. Mistake #2 was that I put 1 tsp of gypsum per gallon instead of 1 tbsp. Doh! Do you think I should add a bit more to the top of soil I can reach?

But, anyway, it's my first attempt! Yay! :-)

My redbud is now in the 62 qt. pot with this stuff. Hopefully it lives cuz my instructions for the tree said to keep it in the soil it came with but I totally took all of that off of the roots before putting it in this mixture.

I did add osmocote plus to the top couple inches of soil.

I have yet to add epsom salt though since I wanted to double check if I should --- the osmocote plus contains 1.9% Ca and 1.4% Mg. Should I still add the full amount of epsom salt you originally recommended?

Also, how often should I water this tree with gritty mix? Is it as easy to feel by touch if it's still wet?

I also can't help but wonder if I should've added some "Soil Moist polymer granules" since in the summer southern heat we often have droughts that prevent water usage. What are your thoughts on this? I recall reading that if I let this gritty mixture dry out it will lead to it not wanting to retain moisture again. (Sounds scary.)

I still have the dogwood to plant so hopefully I can get it better the second time! :-) And I'm also hoping I don't need to dig up the redbud and redo it...

Second try... this time I used pine bark fines and screened them:

{{gwi:19340}}

My pine bark is flat, so do you think this size is ok? Or do I need to find a big screen and double screen it to get the tiny fines out and the bigger chunks? (Not sure where to get the larger screen if I need it though.)

Also, I ended up with growing & layer gran-i-grit since that's all they had (besides starter) so I mixed them together. The layer is larger, which might help match the size of pine bark. Have you ever used the layer kind?

Plants will love it if you can keep up with their water requirements. The suggested particle size of the original recipe (sounds like KFC) is designed to allow the most water retention possible w/o a perched water table. When you increase the particle size, you reduce water retention, which is still just fine according to what your plants will tell you, but you might find yourself grumbling about the frequency with which you'll need to water in order to keep your plants off your back. ;o)

Al

Ahh, ok. So the redbud shouldn't keel over in my bad first mix, it will just need more water. I guess I'll just wait to see how much more it really needs and figure out if a replant is in order later.

What about the epsom salt question though -- since the osmocote plus contains 1.9% Ca and 1.4% Mg, should I still be adding the full 1/4 - 1/2 tsp/gallon?

[I think this works out to be like 4 cups of epsom salt for the 15 gal pot, which seems like a lot!]

Thank you so much for your help with this so far! Luckily, today I found another location ("Southern States") that carries Gran-I-Grit - and they weren't sold out of the grower size!

Ohhhh Nooooo! ;o) You misunderstood the dosage. You add 1/4 - 1/2 tsp of Epsom salts per gallon of fertilizer solution whenever you fertigate (fertilize + irrigate = fertigate) your plants.

In this particular case, since the Mg in the Osmocote is already quite high in relation to the Ca, you can probably skip the Epsom salts with no problem at all. The Ca:Mg ratio should (ideally) be somewhere around 3-4:1, Ca:Mg.

Al

Oi! Now I'm really confused! :-) How often & how much am I supposed to be fertilizing?

The osmocote plus says once every 6 months and the container is only like 4 pounds. If you're measuring this stuff per gallon... and fertilizing every time you water (irrigate = water, right?)... eek?

My main paranoia here is that I'm going to mess up the nutrient part for my little growing friends. I just sprinkled the osmocote all around the top of the container, worked the beads into the top inch or so and watered, thinking I don't need to do that again for another 6 months... Am I wrong?

I do like the simplicity of skipping the epsom salt at least. :-)