Hydrangea macrophylla -- Bigleaf Hydrangea

• Macrophylla means "big leaf" in Latin. This is the largest and most economically important species. To most gardeners, "hydrangea" is synonymous with this particular species. Most cultivars of hydrangea macrophylla bloom on the previous season's wood. If you live in a cold zone and the flower buds are winter-killed, most likely you will have no blooms. Recent breeding programs have developed macrophylla types that bloom on both new and old wood. This will produce flowers from mid-summer all the way through fall. An example of ever-blooming hydrangeas is the 'Endless Summer' series developed by Bailey Nurseries, Inc. Pruning of this species should be done immediately after bloom. Pruning this species in the winter or early spring will remove the flower buds set the previous fall.
  
  

Hydrangea paniculata -- Panicle Hydrangea

• The flower heads of panicle hyrangeas are often so heavy, they weigh the branches down.Hemera Technologies/PhotoObjects.net/Getty Images
  
  As the common name dictates, panicle hydrangea flowers are born on 6 to 8-inch-long panicles, or cone-shaped flower heads. Hydrangea paniculata is the most cold-hardy of all the hydrangea species and blooms on new growth starting in mid-summer. The flowers will last 4 to 6 weeks (sometimes 8) and turn from a creamy white to pink, bronze or even purplish. Pruning for this species should be done in late winter or early spring.
  
  

Hydrangea quercifolia -- Oakleaf Hydrangea

• Oak trees are in the genus Quercus, which explains the species name quercifolia. Oakleaf hydrangeas have many ornamental attributes including exfoliating bark, beautiful fall color, leaf texture and some unusual flowers. This species typically blooms from June to September on old wood. Flowers of this species are 4 to 12 inches long ranging in color from bright white to almost red. Hydrangea quercifolia puts on a fantastic show in the fall with the foliage color ranging from red and orange-brown to burgundy. This species should be pruned back after flowering.
  
  

Hydrangea anomala -- Climbing Hydrangea

• The species name anomala means "irregular, or deviating from the norm" in Latin. Several characteristics make this species of hydrangea "unusual." First, this is a climbing form of the genus, growing up to 80 feet tall and attaching itself to structures using root-like structures. The secondary branches that form help the vine look shrub-like, creating a full effect on a structure. The flowers appear in early to mid-summer and are displayed in a corymb, or flat topped flower form.