I slip the whole root-ball, original soil and all, into a one-gallon pot full of bark and a little perlite.
Then, toward the end of winter, I formally bare-root the seedlings (cleaning away old soil) and re-pot.

Josh

Hey Josh,

Thanks for the info. I take it that you have had success with that system? I'm thinking about issues that can arise from different types of soil in the ball surrounding the central roots and in the outside. What kind of bark do you use?
I hope that you don't mind all of the questions, but how do you go about cleaning the roots off? Do you have a particular protocol or is it pretty self explanatory, brush em off, etc. I've been poking around and i haven't found as of yet a description that was clear to me of how to go about bare rooting. Maybe it's because I'm somewhat obsessive but i like to have a plan of action.
Thanks again for your response.

- Michael

Hey, Michael!
Bare-rooting is a pretty easy process. Just tip the maple out of the pot and gently loosen/unwrap the roots. Hose the roots off until most of the old soil is gone. I prefer to work on a cloudy day (or else in the shade). Of course, you'll want to have a proper soil-mix prepared ahead of time for the re-potting.

In mid-June 2008, I collected my first maple seedling.
The root-ball was basically packed in this grey clay-like soil, and I didn't want to expose roots in the heat. I used a pine/fir bark mulch - the small stuff, decorative ground-cover. I think it was Micro Bark, by Greenall. Pure bark worked just fine. Here's a pic of that first seedling:

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Last summer, June-July 2009, I collected even more maple seedlings with this method - most of which were kept over winter and given to friends this spring. The only difference is that I now buy bags of "fine" grade Orchid Bark (an E.B. Stone product). I also started adding Perlite and pumice to the bark. Here's a pic of last summer's batch:

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During the winter, the trees were placed near a wall. It doesn't get real cold here, but these maples are at 2,300 feet elevation. One maple was simply slipped into a terra cotta pot, and bark was poured between the two for insulation and moisture. That maple, with the extra warmth, really wintered the best.

This was in early May. The trees have been pruned hard since, and are still growing like crazy. After this season, they'll need to be re-potted. Those in large containers will have their roots pruned and will get fresh soil - but they'll go back into the same sized pots.

Josh