A Greene County Garden in Fall

By Margaret Donsbach Tomlinson

Many gardeners prize hydrangea shrubs for their beauty and easy-going nature. Most originate in Asia, including the fussy blue mopheads that need regular adjustments to keep the soil acid. Two hydrangea species native to the eastern United States, though, make outstanding garden shrubs.

Most hydrangea lovers are familiar with the oakleaf hydrangea (Hydrangea quercifolia), a deciduous shrub native to woodland habitats in the southeastern United States. It also grows well in areas somewhat north of its native range, including the Hudson Valley, slowly reaching a mature size of 4-8 feet tall and wide. Its long-lasting white flowers appear in dramatic cone-shaped clusters and turn pink in the fall, while its leaves turn a striking bronzepurple. Numerous cultivars have been developed, some dwarfed to fit smaller garden spaces, some tinkered with to produce brighter flower and leaf colors. If one of your reasons for planting native shrubs is to attract butterflies and other pollinators, you may want to focus on the straight species rather than a cultivar or hybrid, for its higher quality nectar.

Another native hydrangea is sevenbark or smooth hydrangea (Hydrangea arborescens). It grows faster than oakleaf, to 10 feet tall and wide at maturity. Its native range is somewhat larger, favoring streambanks and wooded slopes from New York south to Florida and west to Louisiana and Iowa. The flowers are not as showy as its oakleaf cousin, resembling a lacecap hydrangea with a few large, sterile florets at the edges of the flower clusters. Cultivars have been developed with showier flowers, but gardeners keen to attract the hydrangea sphinx moth, with its curvy green or golden-brown wing stripes. may want to stick with the species, a host plant for its caterpillars.

Other hydrangeas native to the U.S. include silverleaf (Hydrangea radiata) and ashy (Hydrangea cinerea) hydrangeas. Both are native to the southeast, the silverleaf to the southern Blue Ridge Mountains, and the ashy from South Carolina south to Alabama and east to Illinois. Their flowers are similar to those of the smooth hydrangea; both were considered to belong to that species until botanists distinguished subtle but key differences. The ashy hydrangea is a smallish shrub, 3-6 feet, while the silverleaf will reach 4-8 feet at maturity. For gardeners coping with a black walnut tree, it’s worth knowing that silverleaf hydrangea, unlike many plants, will grow under black walnut.

Most hydrangeas prefer moist soil, tolerating some drought when established, but the ashy hydrangea is more drought-tolerant than most. We don’t know for sure what to call my neighbor’s hydrangea, planted years ago by a previous owner. Based on its size and the shape of its leaves, it’s likely to be a cultivar or hybrid of smooth hydrangea. In any case, it’s lovely!

Margaret Donsbach Tomlinson enjoys gardening in Catskill. She also writes a weekly Substack series, The Generous Garden, online at mtomlinson.substack.com.