Answer: There are a number of small trees that would suit such a spot with clay soil and hot afternoon sun. You might try some of the smaller and newer disease resistant crabapples, the native redbud, or perhaps a smaller ornamental cherry. No matter which tree you select there will be a certain amount of competition for light, water, and nutrients so keep this in mind while selecting the surrounding plants. It is also a good idea to spend extra attention on preparing the soil and then maintain a layer of organic mulch to help "feed" the soil on an ongoing basis.
Q&A Library Searching Tips