Hydrangea has grown to be one of the most popular perennial plants in American gardens, and the variety that is available now is quite impressive. There are actually twenty-three species of Hydrangea, and of these only five are generally available in the United States. These five species, however, represent a broad variety of available plants, from the wildly popular Garden Hydrangea to the unique Climbing Hydrangea meaning that growing Hydrangea is a great option for nearly any gardener.
The most common and familiar Hydrangea is the Hydrangea macrophylla, more commonly called Garden Hydrangea or French Hydrangea. This plant is popular not only for it's huge bounties of flowers, but also because the color of its flowers can actually be changed from pink or red to white or bright blue, all with simple adjustments to the soil pH and aluminum content. Because Garden Hydrangea produces buds in the autumn and flowers in the spring, care must generally be taken to protect those buds from freezes in early fall and late spring. However, in recent years several cultivars have been developed which can produce buds on new wood in the spring, meaning that these new varieties can still flower even if the cold kills the buds.
Hydrangea
The most cold-hardy specie of Hydrangea is the Panicle Hydrangea, Hydrangea paniculata. Because these Asian natives are the largest type, growing as tall as fifteen feet, they are often pruned into tree form, and are sometimes sold as "Hydrangea trees." Panicle Hydrangea bloom in mid-summer with large white flowers on six- to eighteen-inch panicles. The flowers of Panicle Hydrangea often mature to a light pink color.
The larger of the two Hydrangea species native to the United States is the Oakleaf Hydrangea, Hydrangea quercifolia. Oakleaf Hydrangea produce four- to twelve-inch panicles of large white blooms in early summer. Like the Panicles, these blooms often mature to a pink or rose color. The Oakleafs are best known, though, for their beautiful foliage, which color in fall to a lovely, deep bronze. It is the only Hydrangea that produces significant fall color.
The other native specie is the Smooth Hydrangea, Hydrangea arborascens. It appears naturally from New York all the way to Florida and Louisiana. Smooth Hydrangea are nearly as cold-hardy as the Hydrangea paniculata, but they can survive much warmer areas (all the way to zone 9). These shrubs only grow to about five feet in height, and they are often used in mass plantings, where the white midsummer blooms have the most striking effect. The blooms of the Smooth Hydrangea mature to a lovely pale green.
The most unusual specie is the Climbing Hydrangea, Hydrangea anomala. It is the slowest to bloom of the common Hydrangea, producing white lacecap inflorescences in early or midsummer on established plants. However, Climbing Hydrangea is quickly becoming one of the most sought-after species of the genus in America because it is a true clinging vine. It has been known to cover structures as large as eighty feet tall, and when it is in full bloom the effect is nothing short of spectacular.
Between these five species of Hydrangea, there is one for almost any garden, and more, interesting cultivars are being produced every year, ensuring that Hydrangea will remain one of the most popular flowering perennial plants for many years to come.
From Climbing Hydrangea to Oakleaf Hydrangea - Types of Hydrangea Plants