Answer: You might be able to use a smaller growing variety of crabapple, a small deciduous magnolia, Cornus kousa, or possibly an upright Japanese maple. Keep in mind that even deep rooted trees will also have spreading roots that extend beyond their branch tips. I am not exactly sure what you mean by an umbrella effect, but your local professional nursery staff and/or county extension may have additional or other suggestions based on a more detailed understanding of the growing conditions where you want to plant and your overall design goals. Also, according to your zip code you are gardening in zone 6B, the warmest part of zone 6. Enjoy your new tree!
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