For many years now Hydrangea has been one of the most popular perennials in American gardens. The variety of these great shrubs that is available now is quite impressive, far from being just the one-colored puffballs that you remember from your grandmother’s garden. There are 23 species of Hydrangea, but of these only five are widely available in the US. The five that are available, though, represent a great variety of flowering perennials, with an option that is right for almost any American gardener.
The Hydrangea that you’re most likely familiar with is the Hydrangea macrophylla (more commonly called Garden Hydrangea, French Hydrangea, or just Hydrangea). These plants produce impressive bounties of flowers. In many Garden Hydrangeas, the color of the flowers can be changed from red or pink to white or bright blue by adjusting the chemical content of the soil in which they’re growing. Garden Hydrangeas have come a long way in recent years, including several new cultivars that now produce buds on new wood in spring, which allows them to flower even if they autumn buds are killed in the winter. Many of the new varieties are much more interesting, as well, including the Miss Saori Hydrangeas and Blue Enchantress Hydrangeas.
Panicle Hydrangeas (Hydrangea paniculata) are the most cold-hardy of the common species. They are the largest type as well, some growing to fifteen feet. These Asian natives are often pruned into tree form and sold as “Hydrangea trees.” They bloom in mid-summer, usually with large white flowers on six- to eighteen-inch panicles. In some varieties of Panicle Hydrangea the white flowers mature to pink.
There are two species that are native to the US. The larger of the two is the Oakleaf Hydrangea (Hydrangea quercifolia). Much like the Panicle Hydrangeas, Oakleafs bloom with large white panicles that mature to pink or rose. These flowers come sooner, in early summer, and are smaller, on four- to twelve-inch panicles. Oakleaf Hydrangeas are unique, though, in that they are often grown primarily for their beautiful foliage, which matures to a deep bronze in fall. Oakleafs are the only common Hydrangea to produce significant fall color.
The smaller American native is the Smooth Hydrangea (Hydrangea arborascens). These can be found in the wild from New York to Florida, and are nearly as cold-hardy as the Hydrangea paniculata. Smooth Hydrangeas have the advantage over the Panicles, though, in that they are much better adapted to warm weather. Smooth Hydrangea grow to four or five feet high and in early to mid-summer produce large round clumps of bright white flowers that sometimes mature to a lovely pale green. These shrubs are most often used in mass landscape plantings to striking effect.
The fifth (and most unusual) specie is the Hydrangea anomala, or Climbing Hydrangea. These are true clinging vines that can grow to astonishing size. They’ve been known to climb structures and buildings as high as eighty feet tall, which, in full bloom of large white lacecaps, is a truly awe-inspiring sight.