Natives of North America and East Asia, hydrangeas (Hydrangea arborescens, H. macrophylla, H. paniculata, H. quercifolia) offer extravagant blooms for a variety of environments from zone 4 to 9. Their forms include climbing, shrub and wild forest giant. They produce multi-flower blooms in flat, "mophead" and cone shapes. They need full sun in northern climates and dappled shade in the South.
The color of flowers on big-leaf hydrangeas, H. macrophylla, depends on the aluminum content of the soil. Acidic soils make aluminum available, and hydrangeas in acidic environments bloom blue; those in alkaline soils bloom pink. Cultivars take the colors to extremes of red and violet. The cone-shaped blooms of H. paniculata start out white and mature to rosy-pink in the fall. H. arborescens, wild hydrangeas, have white flowers. Light up your shade garden with the giant popcorn-ball blooms of H. arborescens, nicknamed "Annabelle."
For year-round interest, opt for the North American native oak-leaf hydrangea (H. quercifolia), named because their leaves are shaped like oak leaves. They'll give you deep green spring leaves, summer clusters of white to pink flowers, blazing burgundy fall foliage, and peeling, cinnamon-colored bark in the winter.
See the next page for another lavish bloomer.