Honeysuckle Species in Pennsylvania

180 species of honeysuckle (Lonicera spp.) exist in the Northern Hemisphere. They include several exotic species that are now considered invasive in Pennsylvania and six native species, including several that are in trouble. There are also three very nice, vining species that would be welcome additions to gardens across Pennsylvania: one is native, one naturalized, and one is a non-native yet non-invasive species.

The invasive species of honeysuckle have been introduced from Asia, mostly China and Japan, and consist of six species of shrubs and one vining species. The shrubs are fragrant and include winter (Lonicera fragrantissima), Amur (L. maackii), Morrow's (L. morrowii), Bells (L. x bella), Standish (L. standishii), and Tatarian (L. tatarica). Each of these shrubs can grow to be 6 to 20 feet in height. Their stems have an inner, hollow, brown pith. The vining Japanese honeysuckle (Lonicera japonica) grows 16 to 29 feet high and 3 to 6 feet wide. It can smother plants that it climbs over. It, too, has a hollow stem pith. Native species do not have hollow stem piths; they are all solid.

Of our Pennsylvanian native species, two are classified as "Endangered," and one has an even more ominous status of "Tentatively Undetermined." Endangered Lonicera oblongifolia, or swamp fly honeysuckle, is an upright 4-foot-tall wetland shrub with pairs of yellow flowers that are followed at the tips of the stems by red berries. Endangered Lonicera villosa, or mountain fly honeysuckle, is the only other wetland honeysuckle shrub. It has creamy yellow flowers and blue berries and grows up to 5 feet tall. Hairy honeysuckle (Lonicera hirsuta) has the classification of "Tentatively Undetermined." This vining species has the hairiest leaves and yellow flowers borne in clusters. It was found in woodlands and thickets, particularly at higher elevations. The native Lonicera canadensis, American fly or Canada honeysuckle, is also a shrub. It prefers forests and forest edges and grows to 5 feet tall. Its pale-yellow. tubular flowers are followed by small, oval, red berries. American fly honeysuckle is considered extirpated (believed extinct) in Indiana and endangered in the bordering states of Maryland and New Jersey.

Three Vining Honeysuckle Species Worth Growing

The following three species are exceptional garden plants. As vines, they will provide a vertical element in the garden, but could also be trained to scramble along the ground, in and amongst other plants. Their tubular flower structure and colors are quite attractive. The flowers are followed by colorful berries, continuing their visual interest through the season. These honeysuckles also create important habitat for and provide food for much wildlife. Common characteristics exist. All three species can be propagated by layering, stem cutting, and by seed. All have 1- to 3-inch long, simple, opposite leaves with entire (smooth) margins. All have twining stems that twist around supports and need strong structures to climb, be they fences, trellises, arbors, wires, or tuteurs. All are resistant to deer and the toxic effects of black walnut trees. All three are available commercially, though one has no cultivars.

Lonicera dioica

This non-threatened, vining honeysuckle is native to Pennsylvania. Lonicera dioica is commonly known as limber or wild honeysuckle. It grows in cooler areas from USDA Hardiness Zones 3a to 5b and prefers silt, sandy, or shallow rocky soil, with a neutral pH, and full sun, part sun, or dappled shade. This species is the shortest of the three, topping out at 3 to 10 feet tall and 3 to 6 feet wide. Limber honeysuckle flowers in late spring. Its less than one-inch, non-fragrant flowers are trumpet or tubular in shape, and are borne in whorls at the end of the branches. Their color varies from gold, yellow, orange, purple, lavender, red, and burgundy. Small ¼- to ½-inch orange to red/burgundy berries appear in early summer. The leaves are medium green with white undersides. Limber honeysuckle is very valuable to wildlife. Flowers attract hummingbirds and bees. Songbirds consume the nutritious fruit (though the berries are toxic to humans) and disperse the seeds. This honeysuckle blooms on old growth, so wait to prune it until after flowering/fruiting. The species is available commercially, but there are no available cultivars.

Lonicera sempervirens

The coral or trumpet honeysuckle is native to the southeastern United States, but this lovely plant has naturalized in Pennsylvania and elsewhere. There are many cultivars that provide different colors of flowers, length of blooming, and disease resistance. It grows comfortably from USDA Hardiness Zones 4a to 9b and prefers loam or clay soils that are high in organic matter with a neutral to acidic pH. While coral honeysuckle will tolerate shade, the blooms will be more plentiful in full sun. This is a large vine, topping out at 10 to 20 feet tall and 3 to 6 feet wide. Its gorgeous 1- to 3-inch, non-fragrant, trumpet-shaped flowers bloom from spring through the early fall, depending on the cultivar. They are borne in whorled clusters at the end of the stems. Their color is also cultivar-dependent and varies from gold, yellow, orange, red, and burgundy. The small, showy, red-to-black berries appear in late summer to early fall. The leaves are blue-green and are evergreen in their native southern habitat, hence the specific epithet sempervirens (always green). This honeysuckle is very valuable to wildlife. Hummingbirds, including the Ruby-throated hummingbird, and other pollinators such as bees, butterflies, and some moths are attracted to the abundant flowers. Songbirds consume the nutritious fruit (though the berries are toxic to humans). It is a larval host for the snowberry clearwing moth (Hemaris diffinis) and the spring azure butterfly (Celastrina ladon). Some cultivars have been developed to bloom on new wood, so be aware of this prior to pruning. Coral honeysuckle can be bothered by aphids and powdery mildew. Please note that this species is classified as extremely flammable, so do not grow it near valuable structures.

Notable Cultivars

• Lonicera sempervirens 'Alabama Crimson' – Deep red flowers
• Lonicera sempervirens 'Major Wheeler' – Scarlett flowers bloom heavily over a long season
• Lonicera sempervirens 'John Clayton' – Yellow flowers bloom on and off through the season
• Lonicera sempervirens 'Sulphurea' – Yellow flowers
• Lonicera sempervirens 'Cedar Lane' – Scarlett flowers rebloom on new wood. Resists aphids.

Lonicera periclymenum

This species is known as common or European honeysuckle. While it is native to Europe, it has naturalized here and is not considered invasive. It grows from USDA Hardiness Zones 5a to 9b and is not picky about soil pH or structure. It will grow in clay, loam, or sandy soils, as well as those with high organic matter. European honeysuckle tolerates sun to shade, though it really prefers dappled shade where its roots are in the shade and its tops climb into the sun. Like coral honeysuckle, this is a large vine, topping out at 10 to 20 feet tall and 3 to 6 feet wide. The flowers are 1 to 3 inches long. They are classified as lipped and tubular and are borne in whorls at the end of the branches. While they are fragrant (especially in the evening), their season of bloom is limited to the spring. Their color is also cultivar-dependent and varies from white, cream, yellow, pink, and lavender. It flowers on old growth. The small ¼-inch deep red berries develop in late summer to early fall. Its leaves are dark green. The flowers of this honeysuckle attract hummingbirds, bees, butterflies, and some moths. It is a larval host for the red admiral butterfly (Vanessa atalanta).

Notable Cultivars:

• Lonicera periclymenum 'G.S. Thomas' – Creamy white to yellow flowers. Fragrant, especially in the evening.
• Lonicera periclymenum 'Berries Jubilee' – Fragrant white to yellow flowers, followed by a profusion of bright red berries
• Lonicera periclymenum 'Serotina' – Crimson-budded flowers with creamy-yellow throats
• Lonicera periclymenum 'Belgica' – White flowers that turn deep yellow and are streaked raspberry-red outside