Dahlia imperialis Family: Asteraceae Common Name(s): Grown by: Don Mahoney, Richmond (The purple flowers on the left) From southern Mexico through central America comes this giant dahlia species. The tree dahlias are usually 10-15’ tall with 4-8” flowers. The one shown had 9” flowers. Many seedling forms are available, from white to deep pink, and in both single and double pom-pom forms. They are evergreen but will stump sprout if cut to the ground by frost or a zealous gardener. They bloom from Halloween until Christmas, depending on the clone. The late-blooming ones often are cut short by frost or are toppled by early wind storms. They are best planted in protected spots. Both hummingbirds and bees visit them. Photo by Steve Morse