Raised beds, even raised mounds or berms are very common landscaping practices, especially in areas with hard to work soil conditions. I can think of no reason why Japanese maples could not grow in these circumstances - I've utilized them in this manner myself.

"Making" your own soil may not be at all practical under these conditions. First, depending on how large your raised bed or mound is, you will likely need soil in quantities larger than you can easily put together from whatever you have on hand. Since you live close to a large metropolitan area there are bound to be bulk soil providers nearby. Explain what you are doing and they will help you determine how much and what kind of product you need. Most will deliver as well.

FWIW, the beds don't need to be that deep. A foot or so is more than adequate. Drainage is always improved under these conditions just by virtue of the elevation and then also by the better textural quality of the planting mix you fill then with.

I'm not sure what your concerns are with air circulation. You should plant the trees or whatever no closer to any structure than half their mature spread. And if lower growing, allow sufficient maneuvering space to get behind them for any maintenance issues. Other plants are not an issue unless they are encroaching into each other.

Again gardengal, thanks!!! You have so much knowledge.. this will be another next year project... I haven't much good soil as present, and compost breaks down. This year can't afford to order from company, plus where they'd dump it, I couldn't physically get it where needed (up, up, up)..

"gardening" is hard work!! Maybe once it's established it's easier, but I doubt that..

Again, they'll need to be in their pots and overwintered, I again am afraid I'll kill...

THANKS!!!!

Amy

greyandamy, I make my own soil. Seriously.

I have many raised beds. Do a search on Lasagna Gardening and you'll have all you need to know.

In the meanwhile, my 1st and most well established beds were made with layers of:
cardboard
hay
newspapers
2" of leaf grow or plain dirt
magazines
wood chips
newspapers
2" of more leaf grow or dirt
paper bags of house waste like Kleenex, paper towels, mail, cat poop (No veggies for me!)
newspaper
2" of dirt.

I think you catch the theme here. Nothing protein.
I would water or let the rain mash down the layers each time.
when I was about 1" above the top (could have gone higher) I used leaf grow for the last, thick layer. I planted in that layer.

One fall the tree chopping people left me a huge pile of chips. I "mulched" all my gardens with them and hated the look. I topped them off with dark mulch, which I loved. by the spring, all the chips were gone.

I have the darkest, richest garden bed soil ever. As we speak I'm collecting stuff to put into my newest, planned bed. It'll home 3 JMs, along with peonies, sedum, and other things I'm moving from other gardens I can't see.

Address the sinking with more layers of leaf-grow, your own paper waste, and top it with mulch, maple leaves, or more leaf grow. You'll be just fine.

Oh - Amy. You can bury your pots in this whole lasagna mess and your plants will overwinter just fine. I've done it for 10 years now.