Common ninebark (Physocarpus opulifolius) is a versatile flowering shrub widely used in landscaping. It gets its name from its bark, which can be peeled off in several (potentially nine) thin layers. Ninebark features dark green or reddish leaves that form an attractive cascading mound. It flowers in late spring with clusters of white or pink blooms, and it bears red fruit in late summer and autumn that often attracts birds.
Ninebark is available in many sizes, with a mature height ranging from 5 to 10 feet with a spread of 6 to 8 feet. There are also dwarf varieties that reach only around 3 to 4 feet in height and spread.
|Botanical Name||Physocarpus opulifolius|
|Common Name||Common ninebark, ninebark, Eastern ninebark, Atlantic ninebark|
|Plant Type||Perennial deciduous shrub|
|Mature Size||3 to 10 feet tall and 3 to 8 feet wide|
|Sun Exposure||Full sun to part shade|
|Soil Type||Clay or loam|
|Soil pH||4.5 to 6.5|
|Bloom Time||May and June|
|Flower Color||Pink and white|
|Hardiness Zones||2 to 7, USA|
|Native Area||North America|
How to Grow Ninebark Shrubs
Ninebark is very easy to grow in USDA hardiness zones 2 through 7, but it might struggle in the heat of zones 8 and 9. The low-maintenance shrub is remarkably tolerant of many growing conditions, including drought, and it is generally free of pest problems and diseases. Occasionally, fireblight and leaf spots might occur, and powdery mildew can strike if the leaves stay wet for a long period. Thinning out older branches can help to improve airflow and prevent mildew.
In landscaping, ninebark is used for specimen planting, foundation planting, hedges, screens, and to prevent erosion on slopes. Many cultivars are available. It's important that a ninebark shrub is given enough space, as well as regular pruning, so its arching branch pattern can be fully appreciated. When used in a mixed shrub border, it works well with lilac and spirea.
Plant ninebark in a location that receives full sun to partial shade, but be aware that it will flower best in full sun. In the northern part of its growing range, the shrub prefers around six hours of direct light each day, but the farther south it grows, it tends to appreciate some afternoon shade.
The shrub can grow in either alkaline or acidic soil, which it prefers to be moist and well-draining. Mulch can help to retain moisture and hold down weeds. As its native habitat includes stream banks, hillsides, and damp thickets, ninebark tolerates clay and loam soil, as well as shallow and rocky soil.
Ninebark will grow in both dry and wet locations. Its water requirements are generally low, but it will handle poor drainage and occasional flooding if necessary. Once established, ninebark is a very good drought-tolerant shrub for dry areas.
Temperature and Humidity
Ninebark is typically tolerant of the various temperatures and humidity levels within its recommended hardiness zones. But the shrub does not like hot and humid climates, which can cause disease in the plant, such as powdery mildew. It can, however, survive through winter temperatures well below freezing.
Spring is the best time to lightly fertilize the ninebark with compost and organic plant food that's designed for shrubs and trees. It only should require this annual feeding. Apply the fertilizer starting a few inches away from its trunk and out to where its branches end.
When necessary, prune ninebark after it flowers or no later than mid-August to maintain its shape and thin out branches. Older shrubs can be pruned close to the ground for winter to renew the plant and encourage better leaf and flower growth. Ninebark tends to bounce back well after pruning.
Varieties of Ninebark
Physocarpus opulifolius is a member of the rose family, which also includes hawthorns and several fruit shrubs and trees. The shrub is found naturally in abundance across the eastern United States, stretching west into the Dakotas and south to northern Florida. Northward, it extends well into Canada. Also, one type is found in the Rocky Mountains and westward to Oregon and Washington.
The ninebark shrub comes in several varieties with different colored leaves, commonly purple and yellow.
- 'Center Glow' has leaves with a golden yellow center surrounded by purple.
- 'Mindina' (also sold as 'Coppertina') displays coppery-purple foliage that matures to a reddish purple.
- 'Monlo' (better known as 'Diablo') bears rich burgundy foliage.
- 'Seward' (or 'Summerwine') has compact purple leaves.
- 'Dart's Gold' sports bright yellow foliage with white flowers in early summer.
- 'Luteus' has yellow leaves that turn to yellowish-green or light green if the shrub is grown in full sun.
- 'Nugget' starts off with deep golden foliage that matures to chartreuse.