Hydrangea Classification

Bigleaf Hydrangea

• One group of hydrangeas, called bigleaf, garden or French hydrangeas (Hydrangea macrophylla), contains plants that are named for their large, deep green, oval leaves. They grow 4-to 6 feet tall and, like all hydrangeas, have flowers borne in clusters, or panicles. Some have blooms called "mopheads," or ball-shaped flower clusters, while others, called "lacecaps", have flowers arranged in flat clusters with an outer ring of larger blossoms. The variety Nikko Blue (Hydrangea macrophylla "Nikko Blue") is a mophead type with 5-inch wide, pink-to-blue flowers in June on a rounded bush, while the cultivar "Lemon Wave" (Hydrangea macrophylla "Lemon Wave") is a lacecap type with pink flowers and variegated, green-and-yellow foliage. Both grow in U.S. Department of Agriculture plant hardiness zones 6 through 9.

Oakleaf Hydrangeas

• Another type of hydrangea is called oakleaf (Hydrangea quercifolia) because it leaves resemble those of the oak tree. This plant grows in USDA zones 5 through 9, reaches a height of 6 to 9 feet and has clusters of white flowers from May until July. Its flower panicles are cone-shaped and up to 12 inches long, maturing from white to a pale pink. The cultivar "Alice" (Hydrangea quercifolia "Alice") has especially long, arching flower clusters and is more tolerant of sun than most hydrangeas, which usually do best in partial shade. Another variety called "Pee Wee" (Hydrangea quercifolia "Pee Wee") is a dwarf variety, about 2 or 3 feet tall.

Smooth Hydrangea

• The smooth hydrangea (Hydrangea arborsecens) is a native American plant that is moderate-sized, between 3 and 5 feet tall, and more frost tolerant than other types. It grows in USDA zones 3 through 9 and is a late-bloomer, producing white, mophead-type flowers from June into September. The cultivar "Annabelle" (Hydrangea arborescens "Annabelle") is about 4 feet tall and has enormous, 1-foot-wide flower clusters that resemble giant snowballs, while the variety called "Grandiflora" (Hydrangea arborescens "Grandiflora") has 6-inch-wide flower heads that are especially abundant and can cover the plant when it's blooming.

Other Types

• Two other types of hydrangeas are commonly grown in the U.S. Climbing hydrangea (Hydrangea anomala) is a vining plant that can produce vines up to 50 feet high. It can also grow as a groundcover, with one plant covering up to 200 square feet. The climbing hydrangea grows in USDA zones 4 through 8 and has white, lacecap flower clusters. The cultivar "Miranda" (Hydrangea anomala subsp. petiolaris "Miranda") has variegated, green and yellow leaves. Finally, the peegee or paniculate hydrangea (Hydrangea paniculata) can grow as a shrub or tree, sometimes as tall as 25 feet, in USDA zones 3 through 8. The plant has upright, pointed and pyramidal flower panicles that begin as white but age to purplish pink. Its foliage turns bronze in fall and it's especially tolerant of urban conditions.