Zone 8 includes a band of Southern states, in addition to a strip through the states on the West Coast and through some of the states on the East Coast. Several varieties of hydrangeas can grow in these areas with no winter protection.
Most hydrangeas grow best in rich acid soil in partial shade to full shade. The leaves often wilt during periods of direct sunshine or intense heat, but regular irrigation can minimize the wilting.
Bigleaf hydrangeas (Hydrangea macrophylla) are also known as French hydrangeas or garden hydrangeas. They have large, coarse-textured leaves and grow 2- to 6-feet tall and wide, depending on the variety. The pH of the soil affects the color of the blooms. Acid soil produces blue flowers, while alkaline soil produces pink flowers.
There are two types of bigleaf hydrangeas. Mophead or hortensia hydrangeas have large ball-shaped clusters of flowers. Lacecap hydrangeas have flowers composed of a center of small flowers surrounded by a circle of larger showy flowers. Both types prefer afternoon shade.
The Endless Summer bigleaf hydrangea has intense pink or blue flowers that re-bloom throughout the season. Nikko Blue has medium pink or blue flowers and also re-blooms.
The flowers of Blue Wave lacecap hydrangea are rich blue or pink, and the large blooms of Beaute Vendomoise are pale pink or blue.
The flowers of oakleaf hydrangeas (Hydrangea quercifolia) begin as a soft green color that lightens to a creamy white. In late summer, the blossoms turn pink, rose or purplish-pink. The large coarse leaves that resemble oak leaves are grayish-green in the spring and turn dark green in the summer. The fall foliage is red, yellow and bronze. Twisted branches and peeling cinnamon-colored bark add winter interest to the garden.
Oakleaf hydrangeas grow 4- to 8-feet tall, and spread by underground stems. They grow best in partial shade to full shade.
The Snowqueen oakleaf hydrangea grows up to 8-feet tall and tolerates more sun than other varieties. Alice also tolerates sun and has large clusters of rose-pink flowers.
Pee Gee Hydrangeas
Pee gee hydrangeas (Hydrangea paniculata) have large conical clusters of white flowers that turn purplish-pink in late summer. They have narrow, slightly hairy leaves and grow 6- to 20-feet tall. The upright stems tend to droop with the weight of the flowers. Pee gee hydrangeas will grow in full sun with adequate irrigation or in partial shade.
Brussel's Lace pee gee hydrangea is a compact plant that grows 5- to 7-feet tall and has lacy flowers. Tardiva has an upright form and blooms later in the season in September and October.
Smooth hydrangeas (Hydrangea arborescens) grow 3- to 4-feet tall and spread by underground stems. They have large leaves, and the heavy mounds of white flowers cause the stems to droop. Smooth hydrangeas prefer partial shade to full shade.
The mounds of flowers on Annabelle smooth hydrangeas can grow up to 12-inches in diameter. Hills of Snow or Grandiflora have a more upright form and 6- to 8-inch mounds of flowers.