Best known for their colorful blue or pink flowers and with over 500 cultivars available, the big-leaf hydrangea decorates many landscapes. But there is more to the hydrangea family than just the well-known big-leaf hydrangea. Hydrangea species also includes a tree and climbing variety. Although different, all hydrangeas have a similar structure when it comes to the flowers. Made up of clusters of small flowers attached by thin stems, the group of flowers is called a panicle. The blooms of the hydrangea make this a popular plant to have.
The big-leaf hydrangea (Hydrangea macrophylla) grows in zone 5B to 9A. This deciduous shrub has big green leaves and forms a round shape as it grows. The flowers make this shrub the main attraction during its summer blooming period. Either pink, blue or white, the flowers change according to the pH level of soil. If the soil pH is acidic, the shrub will have blue flowers. In alkaline soil, flowers will have a purple to pink shade. The color of the flowers will also depend on the variety of the big-leaf hydrangea. The shrub does not have any fall color, but the flowers dry easily for interior display.
The oak-leaf hydrangea (Hydrangea quercifolia) gets its name from the leaves, which have a similar shape as an oak tree. Growing 6 to 10 feet tall, the oak-leaf hydrangea looks nice planted as a boarder shrub or naturalized in a woodland setting. Native in Florida, this deciduous shrub has showy oval-shaped flowers that turn pinkish-red as they age. The only member of the hydrangea family to have fall color, the leaves turn a deep shade of purple to red after the flowers have faded.
A tree hydrangea, panicle hydrangea or peegee hydrangea (Hydrangea paniculata) grows 10 to 20 feet tall. The tree forms a vase shape with branches drooping down, sometimes forming a canopy as the tree ages. More cold hardy than the shrub varieties, the panicle hydrangea grows in zone 4 to 8A. Big white flowers cover the tree in late summer, turning shades of pink that last into the fall.
As a vine, the climbing hydrangea (Hydrangea anomala) has different uses than the shrub and tree varieties. The vine will climb walls and trellises, or grow as a ground cover. The attractive leaves creep and attach themselves with rootlets, small roots that attach the plant to anything it comes in contact with. With heart-shape leaves and summer white flowers, the vine makes for an attractive addition to the landscape.