"I think hydrangea paniculata is the best hydrangea variety to train as a tree form because they're woody shrubs that grow quite large -- the perfect size for a small tree form," Rekola shared.

This tree provides clusters of white flowers in spring, and small, dark berries in fall. It tolerates clay soil and won't ...

Other large shrubs can also be trained as small trees in a landscape, but they do not have the benefits of a native shrub like blackhaw.