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Home » Gardening Information » Great Plants

Bush Honeysuckles—Versatile, Summer-Blooming Native Shrubs for the Low-Maintenance Gardener

Plants & Gardens News | Volume 22, Number 2 | Summer 2007

by Mariellé Anzelone

When I was young, my favorite plant was Japanese honeysuckle (Lonicera japonica), which grew with abandon throughout my suburban New Jersey neighborhood. I was smitten with its sweetly fragrant, tubular white blossoms. Even more enticing (for an eight-year-old, anyway) was the nectar. On our way to school, my sister and I would dally to pluck the flowers, pull out their stigmas, and slurp down the sugary goodness at the base.

It wasn't until years later that I learned about the ecological destructiveness of this exotic vine, which not only dominates many yards and gardens but also invades forests in the eastern U.S., smothering native shrubs and small trees. Nowadays, I'm always on the lookout for more well-behaved alternatives for the garden. Scarlet honeysuckle (Lonicera sempervirens), a native climber, is a good candidate, offering a similar twining habit and scarlet-orange tubular flowers. The related bush honeysuckles (Diervilla species)—with their yellow honeysuckle-like blossoms—are also worthy of consideration.

Rare in the wild, these underappreciated, low-growing native shrubs are even harder to find in horticultural settings. But that may be about to change. Though Diervilla is not a genus that jumps right out and says, "Hey, look at me!" its attractive flowers, long blooming period, lack of pest problems, and happy demeanor in a wide range of conditions make it a no-brainer for today's low-maintenance garden.

A Trinity of Species

Diervilla consists of just three deciduous shrub species, all of them indigenous to open woodlands in eastern North America. Diervilla lonicera (northern bush honeysuckle) is found from Newfoundland south to North Carolina and west to Iowa; Diervilla rivularis (mountain bush honeysuckle), and D. sessilifolia (southern bush honeysuckle) have a more southerly range, occurring from North Carolina south to Georgia and west to Alabama.

Named in honor of one Dr. Dierville (first name unknown), a 17th-century French surgeon and writer credited with introducing Diervilla lonicera to Europe, the genus belongs to the family Caprifoliaceae and shares a fine horticultural lineage with such genera as Lonicera (honeysuckle), Sambucus (elderberry), and Viburnum.

The specific epithet of Diervilla lonicera is an obvious reference to the plant's floristic doppelganger, the true honeysuckle. The species name rivularis means "brook-loving" and refers to a habitat preference of this plant. Diervilla sessilifolia is so named for its almost sessile (or stalkless) leaves.

There's not a whole lot distinguishing the three species from one another. Diervilla lonicera has round twigs and hairy leaf margins; D. sessilifolia sports smooth leaves and arching square twigs; and D. rivularis has square stems but densely pubescent branches and leaves. That's about it, except perhaps for some small differences in flower color (greenish yellow, lemon-yellow, and sulphur-yellow, respectively). Indeed, the taxonomic status of the species is murky, in particular for the latter two, which in the past have been lumped together as varieties of the same species. Genetic studies are needed to sort out the sibling rivalry.

All three species are small-stature, thicket-forming shrubs with arching, vaselike habits, and they grow from two to five feet tall and three to five feet wide. Leaves are opposite, oval to lance-shaped, and finely toothed. Emerging foliage has a coppery hue, which then cools to a dark green with reddish remnants. In fall, the leaves are nicely illuminated with yellows, oranges, and reds.

The plants are hardy at least from USDA Zones 5 to 8, with the northern species (Diervilla lonicera) cold hardy to Zone 3. Several cultivars are available with showy foliage and stem colors. See "Diervilla Cultivars" at the end of the article.

Blushing Flowers

Throughout the summer, three-inch-wide cymes of small yellowish flowers sit atop the bush honeysuckle. Each tubular flower consists of a narrow throat opening halfway up into five outward-curling petals. The flowers are bisexual (containing both male and female parts), but they are self-incompatible because the pistil (female organ) is only receptive before the pollen is shed from the anthers of the stamen (male organ). This condition, known as protogyny, facilitates cross-pollination—and thus genetic diversity within the species.

When an insect or avian visitor probes deeply into a bush honeysuckle flower for a nectar reward, it brushes against the male anthers and picks up pollen. It then carries the pollen to another blossom and inadvertently deposits it onto the flower's stigma as it searches for nectar. This sticky upper portion of the pistil extends well beyond the protective lips of the petals, increasing the chances of a successful encounter. Interestingly, not long after pollination, the flowers of Diervilla species deepen in color—to a reddish yellow in the case of D. rivularis—as if blushing from the impropriety!

Diervilla flowers, which open late in the day, are adapted to attract bumblebees (Bombus species) and hawk moths (Sphingidae) as pollinators. But they have other visitors too, such as butterflies, which sip on the nectar. The shrubs are also a food plant for some caterpillars, including those of hawk moths and the regal moth, Citheronia regalis.

If seed set is successful, a fruit is formed. This beaked, many-seeded, hard brownish capsule matures in late summer and releases seeds in September. Dark and round, like poppy seeds, these germinate easily without pretreatment. Sow seeds directly into the garden in fall for plants that will sprout in May.

Adaptable in Woodlands and Gardens

In addition to dispersing via sexual reproduction, Diervilla shrubs spread dependably via underground stems (suckers) to form dense patches or colonies. This dual reproductive strategy serves them well, as evidenced by their persistence in a variety of environments.

Diervilla species are found in a wide range of habitat types, from exposed, rocky sites to dry and moderately moist woodlands, forests, and cliffs. Bush honeysuckles are just as versatile in the garden as they are in the wild. They seem to prefer dry, relatively infertile soils, but these native shrubs will grow on almost any soil type, acid to alkaline, moist to extremely dry—making them an excellent choice for tough spots in the yard. Though they do best in full sun, they will also grin and bear the shade. They have excellent tolerance for cold, windy conditions.

As a landscaping element, bush honeysuckles can be used for foundation plantings, low hedges, groundcovers, and formal borders. Because they form dense thickets, they can hold soil in place and are thus also a good option for erosion control.

In addition to growing Diervilla from seed, you can also easily propagate the plants through rhizome division and softwood cuttings. Bush honeysuckles are a fickle gardener's friend; since they transplant well and thrive in containers, the shrubs may be moved around the landscape with ease. The only care bush honeysuckles need is pruning once every five years or so. Cut the largest, oldest stems as close to the ground as possible when the plant is dormant, from late fall to early spring.

Diervilla Cultivars

Look for the following bush honeysuckle selections, which expand the foliage and flower color palette of the genus.

Diervilla lonicera 'Copper'
A dwarf selection with coppery-red new growth on stems.

Diervilla lonicera 'Jewel'
Bronze-red leaf color.

Diervilla rivularis summer stars 'Morton'
A dwarf cultivar growing only two to three feet high. Black fruit capsules persist into winter.

Diervilla sessilifolia 'Butterfly'
Deep yellow flowers; glossy green leaves; red to purple fall color; and a neat, well-branched habit.

Nursery Sources:

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