Deciduous Flowering Shrubs - Part 5

When shady gardens are in the summer doldrums, hydrangeas come to the rescue. They are the perfect shrub for shady gardens with two species particularly suited to gardens in cold climates - H. arborescens and H. paniculata. While they will grow quite well in full sun in northern climates, they also grow and flower well in a substantial amount of shade. Dappled shade and / or morning sun with dappled shade the rest of the day satisfies most of them quite well.

Hydrangea arborescens

The smooth hydrangea is often called a 'snowball bush'. This can lead to a fair amount of confusion, since the same common name is also used to refer to H. paniculata and Viburnum opulus - another case where you need to know the botanical epithet to make sure you're getting what you expect.

The species is a floppy shrub with dull white fertile flowers and few or no large white sterile flowers, born on four to six inch (10.15 - 15.23 cm) flattish corymbs. it's not a very ornamental plant and is seldom used in gardens. Native from Iowa to New York and as far south as Louisiana and Florida, it was introduced in 1736. It's often found growing out of rock crevices in deeply shaded woods; Dirr, in his Manual of Woody Landscape Plants says he has seen it growing out of sandstone cliffs in Indiana in shade so deep he couldn't take an effective photo.

The species and all forms sucker from the roots and will eventually cover a large area. You can confine them to an allotted space by cutting off errant bits with a sharp spade - one way to propagate these shrubs. They are all fibrous rooted and transplant well. They are extremely adaptable shrubs as far as soil pH and situation are concerned but prefer rich, well drained, moist soil in partial shade. Rated hardy from USDA zones 3 -9, cultivars of this hydrangea are perfect for those of you in very cold climates.

Hydrangea arborescens subsp. radiata (silverleaf hydrangea) is native to North and South Carolina. It forms a shrub from three to six feet high (0.91 - 1.82 m) with white flower clusters about two to five inches (5.07 - 12.69 cm) across, consisting of both fertile and sterile flowers. Bloom is in June and July. It gets its common name from the extremely white, tomentose underside of the leaves, its most ornamental characteristic.