Common ninebark (Physocarpus opulifolius) is a versatile deciduous flowering shrub widely used in landscaping. It gets its name from the unique exfoliating bark, which peels back in thin layers as the branches mature. Ninebark is a somewhat coarse-textured shrub that features yellow, 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 to give a ninebark shrub 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. Like many shrubs, ninebark is best planted in the early spring while the plant is still dormant. Most people plant them from potted nursery specimens, but you can also buy bare-root or ball-and-burlap plants. Ninebark is a fast-growing shrub; when planted from a 1-gallon nursery pot, it can achieve its full size in just a single growing season.
|Botanical Name||Physocarpus opulifolius|
|Common Name||Common ninebark, ninebark, eastern ninebark|
|Plant Type||Perennial deciduous shrub|
|Mature Size||3–10 feet tall, 3–8 feet wide|
|Sun Exposure||Full sun to part shade|
|Soil Type||Clay or loam|
|Soil pH||4.5–6.5 (acidic to neutral)|
|Bloom Time||May and June|
|Flower Color||Pink or white|
|Hardiness Zones||2–8 (USDA)|
|Native Area||Central and Eastern North America|
|Toxicity||Generally considered nontoxic|
Planting requirements for ninebark are 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.
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 prefers a neutral to slightly acidic soil that is well-draining, but it will tolerate slightly alkaline soils. 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 it will not do well in zones 8 and above. The shrub does not like hot and humid climates, which can cause fungal diseases in the plant, such as powdery mildew.
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.
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. Thus, it is widely cultivated across large areas of North America, and various regions may have their favorite cultivars—sometimes locally developed.
The ninebark shrub comes in several varieties with different colored leaves, commonly purple and yellow.
- 'Diablo' (also known as 'Monlo') is an 8- to 10-foot-tall shrub with chocolate burgundy foliage. It flowers in late spring and is hardy in zones 3 to 7.
- 'Little Devil' (also known as' Donna May') is a dwarf variety, 3 to 4 feet tall with greenish burgundy foliage. It blooms in early summer and is known to have good resistance to mildew. It is hardy in zones 3 to 7.
- 'Center Glow' is one of the more colorful varieties. This 6- to 8-foot-tall shrub has spring flowers of greenish-gold that gradually mature to deep burgundy red in summer. It blooms with white flowers in late spring. It is hardy in zones 3 to 7.
- 'Dart's Gold' is bright yellow in spring, then matures into a deep chartreuse color in summer; in fall, the leaves develop a tinge of bronze. White flowers appear in late spring. This shrub grows 4 to 5 feet tall and is hardy in zones 3 to 7.
- 'Amber Jubilee' is a 5- to 6-foot shrub with orange-yellow spring leaves that turn purple in fall. Hardy in zones 2 to 7, it flowers with white blooms in late spring.
When necessary, prune ninebark after it flowers or no later than mid-August to maintain its shape and thin out the shrub and improve air circulation. Fully one-third of the branches can be cut out with each pruning; focus on older branches, damaged branches, and those that cross and rub.
Older shrubs can be radically 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.
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) 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 developing 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 which 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.
These shrubs, when kept vigorous, are free of most problems. Fireblight, powdery mildew, and leaf spots may occur but are rarely fatal. Badly damaged branches can be pruned away.
The plants can be susceptible to aphids, which can be controlled by spraying with water to knock them off, or by spraying the shrub with neem oil or another organic spray.