Making sense of the honeysuckles

The common plant name “honeysuckle” needs definition. There are honeysuckle vines and shrub honeysuckles. Among the latter are two non-native invasive weeds, one overlooked and underused native species, and another native shrub that is not a honeysuckle at all, as it does not belong to the genus Lonicera. This is an attempt to sort it all out.

The vines

Some of the best honeysuckle vines for Maine gardens are cultivars of the trumpet honeysuckle (Lonicera sempervirens), a species native to the eastern and central United States, including Maine where it is listed as endangered. One of the showiest of climbers, the narrow, trumpet-shaped flowers are scarlet to orange-red on the outside and yellow on the inside. They bring butterflies and hummingbirds to the garden, while the small red berries that mature in fall attract birds.

A mature trumpet honeysuckle vine may reach 15 to 20 feet in height. A new cultivar, John Clayton, is described as even more compact and restrained, never getting out of hand. It has gold flowers that are displayed against blue-green foliage.

Other climbing honeysuckles are cultivated hybrids. For example, a newly introduced hybrid cultivar, Mandarin, produces masses of dark yellow to deep orange blossoms throughout the summer and is hardy to Zone 3. It is fruitless, putting all its energy into flower production.

Gardeners should avoid using any form of Japanese honeysuckle (L. japonica), often sold as Hall’s honeysuckle. This species is highly invasive, and its use is prohibited in most states.

The shrubs

Non-native shrub honeysuckles, including Morrow’s honeysuckle (L. morrowii) and Tatarian honeysuckle (L. tatarica), are noxious weeds. Banned in many states, they have escaped from cultivation in Maine and now present a serious threat to natural areas. Because existing plants are a constant source of seed that birds disperse into wild areas, they should be removed from our gardens and managed landscapes.

A native shrub honeysuckle, the American fly honeysuckle (L. canadensis), grows wild in Maine woodlands as an understory shrub, often limited in size by dense shade but capable of reaching 3 to 4 feet in height and width in more light. Greenish-yellow tubular flowers appear in late May, drooping in pairs from slender branches, followed by bright red berries that ripen in late July. The fruits disappear quickly, a summer treat for forest birds, chipmunks and squirrels.

We found a local source for this native shrub honeysuckle and there are now three plants in Marjorie’s garden, looking at home under oak and cherry in the woodland border. (I would be happy to divulge this source – just get in touch by e-mail.) Perhaps a day will come when most garden centers carry this delightful woodland native.

It may be that the best shrub honeysuckle, at least for some sites, is not a honeysuckle at all. The northern bush honeysuckle (Diervilla lonicera), a native shrub growing to 3 or 4 feet tall, has an upright arching and spreading habit. The new light-green leaves emerge in mid-May, gradually turning to a dark green as the weather warms. In autumn, the leaves turn first to yellow, then orange, and finally red.

Diervilla blooms throughout July with funnel-shaped bells, about a half-inch in length, that are clustered in the leaf axils. Pale yellow at first, they slowly turn to orange or purplish red as they mature. They provide a steady income for native pollinators, particularly bumblebees, during a time of the year when few other plants are flowering.

Thriving in either sun or shade, Diervilla is extremely drought tolerant and can be used in soils ranging from course sands to heavy clays. In Marjorie’s garden it borders steep steps, forming a continuous thicket of foliage and flower that not only holds the soil together but provides ornamental beauty from May to November.

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