Preparing the website
If there is grass under the tree, remove it manually so it doesn’t just grow up through your newly established planting area. Removing it manually is the only way to effectively do this as using chemical herbicide or using a suffocation or solarization method poses danger to the tree. A sharp spade is the best tool; cut the peat into pieces and pry it open to remove it. Pick any remaining grass by hand.
You may want to create a border around the planting area to establish a boundary for your defined planting area. It is a good idea to extend this planting area to the area where good thick grass grows. All types of materials can be used to form edging, including flexible plastic edging, or bricks or stones.
However, there are ways to successfully plant flowers or other ground cover plants under the tree. A small amount of soil and compost added to the ground around the tree will not seriously hinder the tree’s ability to obtain oxygen; in fact, the roots of growing plants will serve to loosen and aerate the soil and actually help the plant get its oxygen. If soil is added very gradually, a tree can easily absorb it by sending new roots up near the surface.
Spread 1 to 2 inches of good quality garden soil over the area, along with 2 inches of compost. In extreme cases, when the area under the tree is dominated by a maze of exposed tree roots, your best option may be to spread a 3-inch layer of mulch over the unsightly exposed tree roots. A layer of fresh compost will do wonders to spruce up your problem area. Then place container gardens over the compost instead of planting in the ground.
It is important to note that some trees are quite temperamental when it comes to disturbing the ground around the trunk. Instead of digging in amendments and installing deep-rooted plants, just spread a small amount of soil over the surface and limit your plant choices to shallow-rooted plants.
