Soil for Japanese Maple in Container

[Spienkow]

I was wondering if anyone had a good soil recipe for trees in containers, Japanese Maple trees to be specific. I was planning on using pro-mix, alfalfa, and mushroom compost. Thanks.

[bullthistle]

Don't have a clue what pro-mix is but manure should be a part but I would be careful about it wintering over because the tree is dormant and it still needs water and if it stays below 32 degrees for too long it could be dead in the spring. If you can bury the container over the winter.