1) Al uses the gritty mix for containers he needs help lifting, and Al is hale. ;o) There really is no upper size limit, even for small plants if you're using a properly made gritty mix because it holds no (or very little) perched water. You need to be a little more cautious about the 5:1:1 mix - especially because there is a wide range in what you end up with as far as porosity/drainage, depending on what goes into it.

2) Over the long term, the gritty mix will outperform the 5:1:1 mix, but they're so close over the short hauls that I put anything 1-seasonal in the 5:1:1 mix. It's easier to make in large volumes and it's much less expensive.

3) It depends on what you use. I screen the Turface because of a size issue. The bark and granite I use are pre-screened, so I screen them over insect screen just to eliminate the dust. That's important to me because I grow many plants in pots an inch deep or less. I need to minimize every form of stress on those plants I can, and can't afford to have a thin layer of sludge at the bottom of these containers. It wouldn't make much difference in the deeper containers most of you would have your long term planting in.

4) "Crushed" is my own term. No 'crushing' is required as it comes in small, pre-screened pieces. I suppose granite chips would be more accurate, but I've noticed that habits are first cobwebs - then cables .... and so I'm prolly tied to 'crushed' unless I make myself think hard about it. ;o)

5) Schultz Aquatic Soil = Turface MVP.

Calcined diatomaceous earth is a little different than Turface. It holds more water (on a size for size basis), has a better CEC, but also has a higher pH. Like unproven sources of calcined clay, calcined DE should be checked for stability by freezing in water over night. If it remains stable, it's ok to use.

FWIW - I have a lot of maples (heavy on the Jap maples but also plenty of tridents & others) in the gritty mix, and have been enjoying very healthy trees for a long while.

Your turn. ;o)

Al

Thanks a lot. I really appreciate the timely and helpful response, especially coming from the man himself.

Actually, I left out one other question I have. Based on my reading, some members have cautioned against "re-potting" after a tree has begun blooming or leafing out, but seem to think that "potting up" (I assume that means moving the tree to a larger pot) is acceptable basically any time. Is my understanding correct on this point?

Again, I really appreciate your generous help, and I look forward to trying the gritty mix.

Josh

Actually, I think they are well thought out and very good questions..

It shows to me that you have been doing quite a bit of reading and research to ask such different questions..I like that!

Mike

".... some members have cautioned against "re-potting" after a tree has begun blooming or leafing out, but seem to think that "potting up" (I assume that means moving the tree to a larger pot) is acceptable basically any time. Is my understanding correct on this point?"

'Potting up' is indeed bumping a plant up in container size with no, or minimal, root disturbance. There needs to be some qualification of the idea you don't repot while the tree is in leaf. That almost always applies to temperate deciduous material, but of course it wouldn't apply to evergreens or tropicals. Evergreens are all over the place, as far as when the best repot time is, and tropicals are best repotted in the month prior to their strongest growth, which varies with latitude and local cultural conditions (if you keep them outdoors). You don't include your zone or a large city near you in your user info (hint hint), so it's difficult to guess when that might be for you. I'll be finishing the last of my tropical tree repots this weekend (only 3 to go), but I'm finishing late this year. I would have liked to have them done by the 4th.

Al

Al- Thanks for the hint; I remedied my zone secrecy. At this point, I'm just dealing with the deciduous maples though. I was just wanting to make sure that potting up wouldn't be a problem this late in the year. But I'm sure it wouldn't be as bad as leaving them in the slightly root-bound state they're in now.

Mike- Thanks for the generous comment.

Josh

What about 5:1:1 vs gritty for bamboo (the real stuff, not the 'Lucky Bamboo') growing in 18"-24" diameter planters?

Bamboo are sort of woody, sort of not. And they grow fast enough that sometimes it's 2 years between repottings, but other times only 1 year.

When you repot the species you're growing - how do you treat them? Do you divide the clump or start over with a few new plants from the perifery?

Al