Ninebark

Size, growth and what to expect

Ninebark builds an upright, mounded shrub of 5 to 10 feet, roughly as wide as it is tall, on arching stems. It grows fast, nearly three feet a year on an average site, which is the rate our growth estimator uses for it. Seedlings first flower in their third growing season.

The flowers come in late May and June in rounded white to pinkish clusters 1 to 2 inches across, like a spirea's, and they have special value to native bees and honey bees. By July they ripen into drooping clusters of reddish inflated capsules that stay on the plant until they shatter in winter, and seed-eating birds pick at them. Older stems shed their bark in papery strips to show reddish brown layers beneath, and the name ninebark comes from the notion that there are nine of those layers.

It grows wild from New York to Minnesota and South Dakota and south to Florida, Arkansas and Kansas, on stream banks, rocky hillsides and ledges, cliffs, fens and woodland edges. It tolerates heat, drought, compaction and road salt.

How to grow Ninebark

Ninebark asks for sun and little else. It stands full sun or part shade and dry, average or wet ground, including a rain garden that floods and then bakes. Bloom thins in shade. Stems arch out wide, so allow 6 feet between plants and keep them off a narrow walk.

Set plants out in the dormant season. Saplings come bare-root or in pots. Dig a wide, shallow hole, hold the crown level with the ground, use the soil you removed, and mulch a ring clear of the stems. Staking a multi-stemmed shrub serves no purpose. Sow seed outdoors in fall an eighth of an inch deep, and seedlings come up early the next spring. For a spring sowing, keep it damp in the refrigerator for two months first.

Water through the first summer and it is on its own. Rabbits nip young stems over winter, so a wire cylinder for a year or two is worth the trouble, while deer rarely bother it. Prune within a few weeks of flowering, since next June's buds sit on wood that grew the year before.

Ninebark appears to need pollen from another plant to set seed, so plant two or more seedlings from different parents if you want seed. Take a few of the oldest canes to the ground each year and the shrub stays full. The one blemish is powdery mildew, a gray film in humid summers, worst where plants are crowded or shaded, and spacing answers it.