They probably said that about the peat because of a tendency for it to break down and become poorly aerated. The solution for this would be to re-pot often enough to keep ahead of the decomposition of the peat. Something that might need to be done at the same interval anyway even if peat was not present. Otherwise any potting mix labeled for use with trees and shrubs should be fine, as long as there isn't something unusual about it like a comparatively high pH.

Or you can make your own out of (mostly) fine bark and (some) coarse sand, with slow release fertilizer added.

Most potting soils are amended to pH neutral. And your maple will be perfectly happy under those conditions. But I'd agree that a peat based potting soil will not hold up well and becomes compacted and excessively moisture retentive. Most growers of trees in containers - any type of trees - will recommend a bark based potting medium. These hold up well, resist compaction and allow for free, fast drainage.

I grow all my JM's in containers - have for years - and I use a bark based potting soil formulated for acid loving plants. It is suitable for any maple, most conifers and broadleaved evergreens as well as the typical rhododendrons, azaleas, camellias and blueberries.

HI thanks for the help.

So can you please send me a link to the product which is basically a bark type potting soil? Or I will be happy to know how I can prepare one? Thanks a lot for the help.

Regards

Potting mixes will vary widely from region to region or area to area. Most national brands - like Miracle Gro - are peat based and should be avoided. If available in your area, I'd look for Farfard's Metro Mix or 52 Mix.

The best recipes for bark based mixes are outlined in this long but very worthwhile thread. It explains in detail the reasons behind and the need for a very durable, fast draining soil mix and will provide several recipes. Either the 5-1-1 or the gritty mix will work well for any containerized tree. The gritty mix will hold up longer so needs to be replaced less frequently.

I only have 4 JMs and a pine and use the gritty mix with great success as well.

Do you think gritty will dry out fast in 95 plus summer heat or should I use more the turface

I much prefer the 5-1-1 for my JM's. Not as fast drainage as the gritty mix but then again not as dire a need to water as often. And I don't have anything near 95F summer heat for more than a day or two, if that, and I still need to water every third day at least.

I also grow all my other trees and shrubs in the 5-1-1. It is the mix that I prefer and just seems to work the best for me.

Anything will dry out fast @ temps >95*. The basic gritty mix uses screened ingredients and equal parts of pine or fir bark, Turface, and crushed granite or cherrystone. You can change the amount of water retention significantly by varying the ratio of Turface:grit. IOW, for more water retention, try

4 parts Turface

3 parts bark

2 parts grit

The additional water retention will come from the fact that you have a higher volume of internally porous Turface and less grit, which only holds water on its surface. In most other media, you need to use peat, coir, or other fine soil components to increase water retention. The problem here is, the additional water retention comes in the form of perched water. Varying the Turface:grit ratio doesn't notably change the air porosity of the soil and doesn't invite a perched water table.

Al

fievel38, I haven't had much problem in that kind of heat. Granted we only get that type of heat for a week or two in the hottest months of the year. I use a top dressing consisting of a handful of leaf mould and some of the larger pine bark chunks that are left over from sifting. The pine bark that goes through the 1/2", but not the 1/4" screen.

Thank you Al and mblan13

garden gal do you add the lime or leave it out?

I don't add lime. Containerized plants are not as dependent on soil pH as are those in the ground and my soil mix is formulated for acid lovers anyway. And JM's tend to favor more acidic conditions.