Hydrangea paniculata is a hardy, reliable shrub that thrives in colder climates. Its flowers aren’t vulnerable to frost damage because they bloom on new wood. The plant usually has tall, cone-shaped flowers. One of the most popular varieties is ‘Limelight,’ a fast-growing shrub that blooms in mid-summer. Hardy to zone 3, this 7-foot-tall shrub produces pistachio-hued flowers that turn deep pink as they age. Other varieties include ‘Pinky Winky’ (bi-colored pink and white), ‘Quick Fire’ (cream to deep red), and ‘Firelight’ (white to deep red). These varieties don’t need extra lime to maintain their pink color.
Hydrangea arborescens, or smooth hydrangea, is a widely branched deciduous shrub that typically grows 3-6 feet tall. ‘Annabelle’ is a popular variety, known for its enormous white flower heads that bloom in mid-summer and dry to a brilliant green. ‘Incrediball®’ offers huge, strong-stemmed flowers with round clusters more than a foot in diameter! This shrub was bred to improve the stem strength of hydrangeas, which often flop under the weight of large blooms. Other varieties include ‘Invincibelle Spirit’ (pink) and ‘Haas Halo’ (white, similar to lace-cap).
Although beautiful, Hydrangea macrophylla (lace cap hydrangea) and Hydrangea quercifolia (oak leaf hydrangea) are only hardy to zone 5 and aren’t suitable for our northern gardens.
Hydrangeas are easy to grow in rich, well-drained soil. They prefer morning sun and afternoon shade. Avoid planting them in hot, dry, exposed areas. Although most people buy hydrangeas when they’re blooming, it’s best to plant them in spring or fall. Prune in late winter or early spring before new growth begins. To get bigger flowers, prune them almost to the ground, leaving a 2–4-inch stem.
Author: Robin Trott, Extension educator, Douglas County