Ninebark (Physocarpus opulifolius) is native to most of the eastern half of the U.S. In the wild, this shrub is often found along streambanks, woods edges, rocky slopes, and moist open areas. Although it is often found naturally in medium to moist locations, once established, ninebark can be very drought tolerant.
In recent years, ninebark has also become an increasingly popular ornamental plant and the horticulture industry has developed a number of cultivars. It is an excellent alternative to planting Japanese spiraea, which is a commonly planted exotic, ornamental species that is highly invasive in many states. (For example, the Kentucky Exotic Plant Pest Council considers Japanese spiraea a significant threat.)
One of the great things about using ninebark as a native ornamental is that it provides year-round interest. Ninebark gets its name from the fact that as it matures, its bark peels away in thin layers to reveal multiple colors of underlying bark. Obviously, this is easiest to see during the winter when there aren’t any leaves to hide the peeling bark.
During the late spring and summer, ninebark produces clusters of white to pale pink flowers. The flowers are highly attractive to honey bees, native bees, and butterflies. (Beekeepers take note – in Kentucky ninebark typically blooms between May and July, so could provide valuable forage after the tulip poplars stop blooming.) After the flowers are pollinated, they are replaced by clusters of reddish fruits that are sometimes eaten by songbirds.
Ninebark is also a host plant for the caterpillars of several moth species. Wild-type ninebark has green leaves that turn yellow in the fall. Some of the new cultivars, on the other hand, can have leaves that range from yellow to dark purple and have more spectacular fall color.
However, I will give one word of caution about planting cultivars of native plants. There isn’t a lot of research about whether or not cultivars of native plants (sometimes referred to as nativars) are as beneficial to pollinators and wildlife as their wild-type ancestors. What research does exist is mixed and sometimes varies based on the species being studied. My guess is that how beneficial a cultivar is compared to the wild-type version is going to vary from one species to the next and one cultivar to the next.
Personally, I am especially cautious of cultivars that change the color of the flowers or leaves. Insects don’t see the world in the same way we do. At least for bees, it isn’t just about the color of the flower. The contrast between the flower and its surroundings plays an important role in how the bee sees that flower. So, if we start changing the color of the flowers or the leaves that surround the flower, then it may affect the way the bees see that flower and thus how attractive it may be to them. (I honestly don’t know enough about butterfly vision yet to know if this could also be true for them, but butterfly vision is on my list of things to learn more about.) Having said that, planting a cultivar of a native plant, even one with different colored flowers or leaves, is still better for the environment than planting an exotic species that is known to be invasive.
In its natural habitat, ninebark typically grows to between 5 and 9 feet tall. In a landscape setting, ninebark can be pruned fairly aggressively to keep it at the size and shape that you prefer. Ninebark blooms on old wood so it is recommended that you prune shortly after the plant quits blooming. The typical recommendation of pruning away no more than 1/3 of the plant at any one time holds true for ninebark. However, if you accidentally mow it down with the lawnmower or get a little too ambitious with the weed whacker, don’t give up hope. Ninebark will often re-sprout the following spring. In fact, chopping it to the ground right before winter is sometimes recommended to rejuvenate older specimens in planted situations.
Ninebark is definitely a plant that I would recommend considering if you are interested in planting a native shrub for pollinators and wildlife. It grows well in a variety or soils, including rocky and clay soils. It can tolerate a variety of moisture levels, although it might need a little more watering until it becomes established in drier soils. And it can grow in anything from full sun to part shade (but will bloom more in sunnier sites as long as it has adequate moisture). Overall, ninebark is a very versatile, native shrub that bees and butterflies love.
This article was part of Shannon’s original Kentucky Pollinators and Backyard Wildlife blog which evolved into the blog for Backyard Ecology.
Backyard Ecology: Exploring Nature in Your Backyard
Nature isn’t just “out there.” It’s all around us, including right outside our doors. Hi, my name is Shannon Trimboli, and I am the host of Backyard Ecology. I live in southcentral Kentucky and am a wildlife biologist, educator, author, beekeeper, and owner of a nursery specializing in plants for pollinators and wildlife conservation. I invite you to join me as we ignite our curiosity and natural wonder, explore our yards and communities, and improve our local pollinator and wildlife habitat. Learn more or subscribe to my email list at www.backyardecology.net.