Can you explain why raised beds aren't an option?

I think what OP is trying to say is that the ground level is probably too high relative to the foundation slab (?) to build raised bed by the house.

Exactly Lou, thank you. And, we can't go too far out with beds either because of the sidewalk.

From Mendocino Maples website -

Clay and poor draining soils

Most maples do not thrive in clay, heavy or poorly drained soils. These types of soils can lead to root rot and bring about disease. In addition plants breathe through their roots and these soil types are not suitable for growth because they are low in oxygen required for good root growth.

If your soil is heavy clay, make the planting hole 2 to 4 inches shallower than the root ball. In poorly drained or heavy clay soil, the plant is best placed higher than its original planting depth at about 4 to 6 inches higher than the surrounding

soil creating a raised mound. Poorly drained soils are a leading cause of plant problems in the landscape. It is a good idea to incorporate about 10-20 percent organic matter into the soil to help with drainage and aeration. Use only well-composted mulches. A quality bag of potting soil mixed in will work just as well. Avoid fine- textured organic matter, such as sand or peat moss. Composted materials immediately provide organic matter to the soil and help with aeration. Do not use green bark products as amendments. Freshly milled bark that has not been composted will slowly rob plants of nitrogen when used as an amendment. As microorganisms in the soil feed on bark and decompose it, they will use nitrogen in the soil. Also, the pH of the soil often drops dramatically below the desirable range when uncomposted materials are used as amendments.

Be sure to build the soil up beside the root ball so that the sides are not exposed, and do not place additional soil on top of the root ball. This will allow oxygen to reach the roots in the upper surface of soil. Do not disturb the soil under the root ball to prevent any later settling, which will move the plant roots deeper into the soil.

Our local nursery has several types of JM I am looking at from bush

What are the names of the bush style?

How much space to you have to plant this Japanese Maple?

It sounds like you may have a limited amount of space?

Maybe it would be a good idea to select a plant that is not a sensitive to soil conditions. Even if you make all the recomended soil adjustments, that may not be enough to correct the conditions.

Mike

Thanks Lou! That's just what I needed. I will try that. Lots of people seem to make maples work here--- I just need to figure out how. This is great advice. Thanks :-)

The amending described above is what we are often forced to do in my area. Our soil is amazingly solid clay and I have seen too many maples die from being planted too deep in our area. One particularly bad spot in my yard took 4 days to completely drain after a heavy rain. If nothing else make sure there is good drainage, I've found a maple can start suffering within in week if it is waterlogged.

Many kinds of maples are adapted to heavy soils and are planted in them by the thousands, as along streets for instance. It is the Japanese maple that is unusually touchy about drainage. If this planting site is big enough your best bet would be to excavate the clay soil and replace with lighter soil. If it is a narrow strip and the area becomes quite wet even that may not work, water coming in from the sides.

Planting a tree or shrub over loosened soil is not a good idea because as the soils settles after planting the new specimen may sink to a level below the desired depth.

Digging organic matter into a heavy soil will not have a lasting effect on the texture of the soil as the organic matter will gradually decompose and disappear. Even when non-decomposing amendments such as sand are used to alter the texture of backfill if the planting area is a small one there will still be the problem of how water moves into and out of the planting area being affected. Small areas of one soil texture surrounded by a much larger area of another are often a setup for problems.

A large bed of soil amended with sand or similar material will also pose the problem of what to do when the dug over area rises up like a loaf of bread after the amendments are dug in - unless a soil already has a fairly high sand content a huge amount must be used to alter the texture of the finished bed significantly.

If you can't excavate and replace a wide area of soil there or put a layer of more suitable soil over the top then it many just be that you can't safely plant Japanese maples in that particular spot. However, since you are in a fairly mild climate zone possibly it would be acceptable to plant them in suitably large tubs and place these on top of crushed rock or other covering in the same location.

After it decomposes, you are back where you were. Periodically re-amended annual and vegetable beds can have the organic amendment level maintained, beds for permanent plantings like trees and shrubs cannot - unless these were to be somehow all dug back up and replanted periodically. And if the area being discussed is a narrow strip in damp heavy soil it is too narrow to amend, being liable to become a collection area for water if given a coarser texture than the surrounding soil.

Why do you think forest soil is black with lots of organic matter? It's because the trees drop their leaves, and then worms and other organisms cycle that organic matter back into the soil. Reapplying good quality hardwood mulch or compost will help maintain the organic matter in amended soils.

It doesn't appear you have enough width between the garage wall and sidewalk to comfortably accommodate a Japanese Maple.
On another note, does the garage have gutters? If so, where do the downspouts eventually put the water?

>Reapplying good quality hardwood mulch or compost will help maintain the organic matter in amended soilsEven if true that mulching can be expected to replace original liberal amending there is still the problem of amending of small areas having adverse effects on movement of water into and out of the amended area, that is what often creates problems for newly planted stock. (Settling as amendments decompose can also be a problem later, as at a local collection where "pit planted" trees and shrubs have sunk below grade over the years).