Return to Plants of Special Interest Page


Hydrangea aborescens ssp. radiata / photo by Anthony Aiello

Summertime Favorite -
Smooth hydrangea (Hydrangea arborescens)

Anthony Aiello
The Gayle E. Maloney Director of Horticulture and Curator

One of the great highlights of the summer is seeing hydrangeas come into flower. If you are looking for a change from the elegant lacecap and bold hortensia bigleaf hydrangeas (Hydrangea macrophylla), then our native smooth hydrangea (Hydrangea arborescens) is a great plant for any garden.

Smooth hydrangea is native throughout the eastern U.S. and across all of Pennsylvania. It is a small shrub, reaching 4-5 feet high with an equal spread at maturity, and it grows well in a variety of conditions. The plants prefer somewhat acidic soils and fairly moist soils, but are forgiving of other situations. One great advantage of smooth hydrangea is that it can tolerate a fair amount of shade. Smooth hydrangea is one of the very few hydrangeas that flower on new growth, which means that you can prune plants in the spring and still have flowers by early to mid-summer. Most readily available varieties of Hydrangea arborescens have clusters (corymbs) of small white flowers – their small fertile flowers are supplemented by showier sterile flowers around the edges of the clusters.

If available, the species type of smooth hydrangea has flower clusters that are three to five inches across and make wonderful additions to naturalistic gardens. More readily available are the varieties of smooth hydrangea, including:

1. ‘Annabelle’ has huge corymbs of sterile flowers up to 12 inches across. These flowers are perhaps too obtrusive for many tastes, and heavy rains may weigh down their branches.

2. ‘Grandiflora’ (hills of snow hydrangea) is a selection from the late 1800s, also with large sterile flower clusters. Old plantings of Grandiflora can form huge beautiful masses.

3. ‘Dardom’ (White Dome™) is a new introduction with large, fine-textured flowers held in stiffly upright branches.

Among all of these, my favorite native hydrangea is the silverleaf hydrangea (Hydrangea arborescens ssp. radiata) found in the southern Appalachian Mountains. It is very similar to the smooth hydrangea species except that the underside of its leaves are covered in dense white hairs, making an excellent show when fluttering in the shade. The selection ‘Samantha’ is a double-flowered form with four to six inch flower clusters.

Because of their relatively small size, adaptability, summer flowering, and ability to withstand pruning, Hydrangea arborescens is useful in a variety of garden situations, including mixed borders and woodland settings.