Sometimes a single plant, not immediately noticed as outstanding, rises to become a garden staple. Usually it is a combination of toughness and adaptability that does this, plus an attractive appearance that fits into lots of different garden styles. Once some different forms, often of new sizes, leaf colors, or flower colors, are developed, then the place of this plant in gardens is assured. That is what happened to the Ninebark, an unassuming wild plant that has become a valuable and even indispensable garden plant. It is used everywhere that reliability, durability, low-maintenance, and a refusal to die are important. With an attractive arching form, neat foliage and interesting flowers and seed pods, plus colorful leaves in many varieties, it is hard to imagine creating gardens in colder regions without it – they certainly would be very much poorer for the loss.
Ninebarks are basic plants for creating structure and form in your garden beds without making work. Since the development of newer forms with colored foliage, they have risen to earn more prominent places too, as stand-out specimens for all-season color without adding garden work to your busy schedule. Because they are so tough you can use them freely. Use the basic form wherever you want some height for background of beds, to create an informal barrier or hedge, and pick more striking specimens to show-case in more prominent positions. Some of the smaller varieties are excellent for edging beds, or in the foreground of larger shrubs. They can be easily clipped into low hedges too.
This is a plant that is equally at home in wet places as it is in dry ones, and it is perfectly happy in difficult urban gardens on very poor soil. It will grow in pockets of earth among rocks, and it survives where almost nothing else will. When all else fails, plant a ninebark. It establishes itself quickly, and once established it is fast-growing, so plants will soon be a good size, and able to contribute to the overall look of your garden. This is an excellent ‘starter’ shrub for new gardens, with slower-growing plants placed near it, so that in time you could remove the ninebarks to allow the other plants to create your final garden.
For natural gardens the Ninebark is an excellent choice, since this shrub is truly native to most of the country. They can be planted in sunny places, on slopes, among rocks and along the banks of streams too. In both natural and more cultivated gardens they are excellent choices for slopes and along water, where their strong roots stabilize the soil and prevent erosion.
Because plants grow quite large, a few is a good way to fill larger spaces in the further parts of a garden, where low-maintenance is a priority, and they can be left to take care of themselves. This is a plant that is almost literally indestructible, and established plants will recover from being completely cut down, and even regenerate after fire.
The common ninebark in its ordinary form is a shrub with tall, arching branches that will grow between 6 and 8 feet tall, and 3 to 6 feet wide in normal conditions, although plants can grow as much as 12 feet tall in ideal locations. The stems sprout from the base, giving a fountain-like look if unpruned, and making a dense clump that will slowly expand without becoming threateningly invasive. The bark is gray-brown, and peels and flakes to give an attractive, rugged look to older stems. You can keep peeling layers of bark away, revealing more below, often reddish, and it is these multiple layers that gave this plant its common name – ninebark(s).
The leaves are attractive, and lobed a little like a maple leaf. They are 1 to 5 inches long, rounded, with a large central lobe and two smaller side lobes. Sometimes there are additional small lobes on the lower part of the leaf. The veins are prominent, and the edges have rounded serrations along them. The leaves are tough and slightly rough, with a semi-glossy surface. In fall they turn yellow, most brightly when growing in full sun, before dropping to the ground. Since they are small they create very little mess.
The flowers come in clusters at the end of short shoots growing from the sides of older branches. Flowering takes place in May or June, and although just 1 to 2 inches across, the dome-shaped clusters of many small flowers are attractive. Each flower is white, or pink in some selected forms, with five petals and a prominent bunch of yellow stamens thrusting out from the center. The flowers are attractive to bees, butterflies and other insects, and a bush on a warm, sunny day will often be swarming with life. Plants may bloom profusely.
After flowering the seed pods develop as drooping clusters hanging from the branches. They are unusual, looking like small inflated sacks, first green, then yellow and ripening between August and October into showy clusters of reddish pods. The botanical name comes from the Greek physa (= bladder) and karpos (= fruit).
From a practical point of view the most striking thing about Ninebark is its hardiness. This plant is reliably hardy even in zone 2, although some of the developed forms may have zone 3 as their lower limit without some damage. This makes it an invaluable landscape plant in zones 2, 3, 4 and 5. It will also grow in zones 6 and 7, but it may struggle in the heat and humidity of the south east in zone 8. In hotter, drier climates it should survive well in zone 8.
Ninebark will grow in full sun or partial shade, and tolerate bright full shade too, although with some loss of vigor. This makes it highly adaptable in gardens, able to grow pretty much wherever it is planted.
This is one plant that is not fussy about soil. It will grow in acid or alkaline soils, including difficult, very alkaline serpentine soils. It grows in sand, loam and clay easily, and even tolerates construction debris, that often makes up garden ‘soil’ in urban gardens. Gravel and rocky soil is part of its natural habitat, and it seems to be just as happy in dry conditions as it is in wet soil, so wherever you need a tough plant, ninebark is your friend.
To allow plants to establish quickly, it is advisable to dig the ground across an area three times the size of the pot, as a minimum. Adding some organic material will give it a good start, and water thoroughly when planting. Water once a week for the first month or two, and after that little or no additional care is needed. If the weather should be very hot and dry during the first year of growth, a deep soaking of water will be appreciated. Established plants are very drought resistant, although dwarf varieties will benefit from water from time to time during dry periods.
As is clear from what we have said so far, the Ninebark is pretty much able to take care of itself. In very poor soils a handful of fertilizer in spring or some organic mulch, will improve growth, but normally even this is not needed.
It is a good idea to choose varieties that will naturally grow to the size you want, and to allow enough room when planting for that final size. That way regular pruning will not be needed, and the natural arching form of this plant can be allowed to develop. You can shorten the main stems at any time, and on older plants it is a good idea to remove a few of the oldest branches at the ground, or close to it, to encourage new, vigorous shoots to grow and rejuvenate the plant. You can also simply wait until the plant has become too big, and just cut it down completely. Established plants will quickly re-sprout.
No pest or disease problems are likely at all with ninebarks. In some seasons a few spots might be seen on the leaves, and a caterpillar or two might make holes in the occasional leaf, but this is always something the plants will shrug off.
Ninebarks belong in the plant genus Physocarpus, part of the large Rose family. Today seven species are recognized, all but one growing in North America.
The Asian ninebark, Physocarpus amurensis, occurs in northern China, Korea and eastern Russia. Perhaps it developed from plants that spread across the land-bridge that once existed between Russia and Alaska. It doesn’t have the conspicuous side lobes seen in American species, and it is never seen in gardens.
All the American species are very similar to each other, with minor differences that are not significant for ordinary garden use. Ones sometimes available are:
Pacific ninebark, Physocarpus capitatus – this native shrub is used mostly in its home state, California, for natural gardens, especially in wet soil and along streams.
Mallow ninebark, Physocarpus malvaceus – also from the West, this shrub is noted for being able to regenerate from the roots after fire.
Mountain ninebark, Physocarpus monogynus – also known as low ninebark, because it grows no more than 4 feet tall, this western species is otherwise like the others.
Common ninebark, Physocarpus opulifolius – this species is widely distributed across most of eastern North America, and we could easily see all the others as just variations on this one species. It is certainly the one almost always grown in gardens, and from which all the decorative varieties have been developed. Several valuable garden forms are available, and they are grown much more often than the wild plant. Among the best are:
Amber Jubilee (‘Jefam’) – created in the cold of Manitoba, this 6-foot plant has wonderful amber-yellow spring foliage that turns green for the summer and then rich purple in fall. Super-tough, reliable and beautiful too, this one is a real winner.
‘Dart’s Gold’ – 4 to 5 feet tall, with spring leaves a bright yellow. They turn greenish yellow for the summer, but still make a bright show.
Diabolo® (‘Monlo’) – tall growing to over 8 feet if untrimmed, the leaves are rich purple from spring to fall. The flowers are pink in the bud, opening white, and the fruits are bright red, showing well against the dark leaves.
‘Lady in Red’ – a variety from England found in batch of seeds from ‘Monlo’. It has pink flowers, and the leaves are a bright coral pink to red all season. Grows to 6 feet.
Little Devil™ (‘Donna May’) – just 3 to 4 feet tall, with attractive pink flowers and rich burgundy-purple foliage that keeps it color from spring to fall, this little beauty is as tough as its bigger parent.
Summer Wine™ (‘Seward’) – just 5 feet tall, with pinkish-white flowers and purplish foliage.
For toughness and durability, the Ninebark simply cannot be beaten. Use the forms with colored leaves to brighten even the most difficult spots. For cold gardens it can’t be beaten, and this is the plant for gardeners who don’t like to garden.