Spotlight: Reblooming Hydrangeas

We usually think of hydrangeas as blooming only once a year, in early to mid summer. But there are some varieties that will put on a second set of blooms in late summer or fall. This is useful not only for a longer bloom season, but to increase the chances of flowering in those years when a cold winter or late spring freeze kill many hydrangea bloom buds.

Several varieties of Hydrangea arborescens, or smooth hydrangea are available. These species, including the popular white flowered variety Annabelle, bloom on new wood, so they can be cut back severely in spring. If the first set of flowers are removed as soon as they fade, they should rebloom in late summer. A popular new pink variety Invincebelle Spirit was developed by Dr. Tom Ranney right here at the Mountain Horticulture Crops Research and Extension Center.

The most common garden hydrangea is probably Hydrangea macrophylla, or bigleaf hydrangea, which sets its blooms on "old wood" the previous summer. The reblooming varieties actually form a second set of blooms on "new wood" during the summer. Varieties such as Endless Summer can be expected to rebloom if spent flowers are removed after flowering, or if they lose the buds in early spring to frost or pruning. For the reblooming hydrangeas to rebloom dependably, they need to be established in the garden and pruned back right after flowering so that about eight weeks of good growing weather exists for new flower buds to develop and open.

The table below lists varieties that happened to be in a test plot at the Mountain Horticultural Crops Research and Extension Center during the winter of 2000 when all of the plants froze to the ground. These still bloomed twice the following summer.

Cultivars of Hydrangea macrophylla that were flowering in July as well as in October 2001 at MHCREC, Mills River, NC North Carolina Cooperative Extension:

For more information, or if you have any questions, contact Buncombe County Cooperative Extension at 255-5522.