Common ninebark (Physocarpus opulifolius) is a versatile deciduous 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.
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.
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, 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 or white|
|Hardiness Zones||2 to 7 (USDA)|
|Native Area||Central and Eastern North America|
How to Grow Ninebark Shrubs
Ninebark shrubs prefer a dry to medium-moisture soil. In cooler climates, it prefers full sun, but in warmer climates, it will appreciate some shade. 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.
Planting requirements for Ninebark is similar to any woody landscape shrub. Dig a hole as deep as the nursery container and twice as wide. Plant the shrub so the top of the root ball is exactly at ground level, the fill in around the root ball with soil, making sure there are no air pockets. Poor soil can be amended with organic material before filling in the hole. Water thoroughly after planting.
This is an easy-care shrub with minimal pruning and feeding needs. It 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.
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, the more it appreciates some afternoon shade.
The shrub can grow in either alkaline or acidic soil, which it prefers to be 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 a ninebark shrub with compost and organic plant food designed for shrubs and trees. This single annual feeding is all that is required. Apply the fertilizer into the soil 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.
Propagating Ninebark Shrubs
Woody shrubs can be tricky to propagate and it can take quite a while (a year or more), but many people find that stem cuttings from ninebark are relatively easy to root. Unlike herbaceous plants, where cuttings must have leaves, with woody plants like ninebark, the cuttings should be taken when the plant is in dormancy.
- In late fall or early winter, cut several pieces of hardwood branch (cane) that are about 1/2 inch thick and 4 to 6 inches long. These should be sections of hardwood, not softwood from the tip of the branch. Each cutting should have at least two nodes (slight bumps on the branch where leaves sprout). Make the bottom cut just below a node and the top cut about 1/2 inch above a node.
- Dip the bottom of each cutting in rooting hormone. Gather the cuttings together and secure them with a rubber band.
- Place the bundled cuttings in a plastic bag filled with slightly moist sphagnum moss or wood shavings. Store the cuttings in the refrigerator to keep them dormant.
- In early spring as soon as the ground can be worked, plant the bundled cuttings in the soil, making sure the tops are facing up. Bury them so that all but the top nodes are below ground.
- Water the cuttings regularly. They will require a full growing season to begin develop roots, but in late fall or early spring, your fully rooted cutting can be dug up and planted in its permanent location.
There are also other methods for propagating ninebark, such as layering. Layering is the process of bending down one of the flexible branches so a portion is buried in the soil, with the tip of the branch is still exposed. When secured in place, the buried portion will send out roots from nodes on the branch. Once the branch has developed ample roots (it can take a full growing season) it can be snipped free of the mother plant and the rooted cutting can be dug up to replant elsewhere.
Varieties of Ninebark
Physocarpus opulifolius is a member of the rose family, which also includes hawthorns, spirea, 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.