Planting Japanese Maples in Wooded Lot
I have about 60 potted Japanese Maples that I was thinking of planting in a clear spot in my otherwise wooded lot. I was told that they would not do very well because of the root competition from the lot's large oaks, maples, and poplars. Therefore, it was suggested that we bring in topsoil and raise the level about 10 inches before planting. But I was also told that this would eventually harm the trees whose roots would now be 10 inches further from the surface. I was thinking maybe of leaving the plants in pots, but killing the grass and placing them on a couple of inches of wood chips or mulch. Would this damage the roots? Is there any particular way to kill the grass that would not damage the roots? Any other ideas as to how to deal with my conundrum? 60 pots cover a fairly large area. Thank you in advance for your wisdom.
The most you can do is give these trees the best chance at survival by meeting as many of their needs as you can, including planning for their eventual mature size. You will need to expect some losses.
Depending on how large your clear area is, you may be fine. There are many types of Japanese Maples and some can do well in large container plantings, so you might try a couple like that.
Your source is correct. You can't pile more than a few inches of soil or mulch over the roots of plants because it stops the roots from getting the oxygen they need.
Take a look here at a recent blog post from our office that should help you with your project: https://marylandgrows.umd.edu/2018/08/24/japanese-maples-in-maryland-landscapes-plant-location-care-...
You can kill back the grassy area using a product containing the active ingredient glyphosate (as found in products like Round-Up) but be careful to follow label instructions as it can kill any green plant it is applied to. Plants/grasses must be actively growing, so you would need to do it soon for this year.
You can't keep these trees in small pots forever. Getting them in the ground will make them happier.
Here is our tree planting information: https://www.extension.umd.edu/hgic/topics/planting-process