*Pine or fir bark screened to 1/8-3/8
Screened Turface MVP or Allsport
crushed granite (Gran-I-Grit in 'grower' size or #2 cherrystone

*If you can find the right size fir bark, 1/8 - 1/4 is best because it's not flat, like pine bark. If you use pine bark, 1/8 - 3/8 is fine.

You can sub calcined DE (floor dry) from NAPA or Carquest for the Turface, and a few other products based on calcined clay or DE if it is the right size. Particle size is important if you want to get the most out of the mix.

2) I have 20+ Acers in containers and use Foliage-Pro 9-3-6 on all of them. It works extremely well for all my trees. It has ALL the 12 essential nutrients plants normally get from the soil (including Ca & Mg, which most soluble fertilizers lack), in an NPK RATIO very close to what plants use and in a favorable ratio to each other. My second choice would be MG or Peter's in 24-8-16, or MG in 12-4-8. All the fertilizers I mentioned have a 3:1:2 NPK RATIO. Soluble fertilizers are easiest to use and have always produced the best results (by far) for me in containers. If you use a soluble fertilizer that DOESN'T have Ca and/or Mg in it, lets talk about how you're going to make sure your plants get it. Adding gypsum to the soil and regular (small) applications of Epsom salts is the best way.

3) Honestly? You should bare-root before the trees leaf out & repot in the new soil, root pruning at that time.

You can use any inert material as a sub for granite, as long as it's right around the 1/8" size.

You'll find more general info below, including some info on root pruning. Acers tolerate it very well, btw.

Al

It's hard to go wrong with a gritty mix for Maples.

Let me speak a little to the question of substituting ingredients, since I started growing
Maples before I had acquired Turface. In my area, Orchid Bark (fine grade), large Perlite,
Pumice (scoria), and Quartz are readily available - so I used these ingredients to make a sort of
gritty 5-1-1, with no peat moss.

When collecting little seedlings and saplings, I simply stuck them into a mix of Bark and Perlite.
But when re-potting, I used the Pumice and the Quartz for water retention, durability, and drainage.
I've helped others re-pot their Maples in mixes of Bark, Perlite, Pumice, and Gravel with great results.
Some mixes have required more frequent watering, and some less.

Substituting ingredients is a lot of work and the variability in product can cause some hit and miss.
While there is much to be said for experimenting with the concepts of drainage and really becoming familiar
with manipulating these potting mixes, it is much easier to follow the formula that has been proven
over the past 20 years.

Foliage Pro user here, too!

Josh

Here's a link that may help. Members have posted and shared where they find the different items for the gritty mix.

I hope it helps.

JoJo

Josh

If you want to understand how water behaves in container soils, which is a very important aspect of container culture, just follow the link.

If you want to read more about maintaining trees in containers over the long term, follow the link below. You'll find plenty of helpful information - I promise. ;-)

AL

Joe

I have about 25 acers to repot this year in new plastic containers ( see pic )and i intend to do it in A1's gritty mix.
( These pots are made by an italian firm, Pasquini & Bini.)
I used what i had at hand i.e. pine bark, crushed high fired clay beads, some perlite and tiny gravel.
My question is about fertilizers, specifically on the subject of adding Ca and Mg.

Adding Mg is fine but i'm afraid to add Ca for i thought Acers didn't like it ?
Thanks.