Japanese honeysuckle (Lonicera japonica) is a hardy but somewhat undesirable plant. In fact, this non-native species is classified as an invasive plant in many states, according to the Invasive Plant Species Assessment Working Group (IPSAWG). The woody vine has semi-evergreen leaves and fragrant, white and yellow flowers. Japanese honeysuckle spreads rapidly through seeds, runners and underground rhizomes, and it can quickly crowd out desirable, native plants if not controlled.
Japanese honeysuckle is cold-hardy to U.S. Department of Agriculture (USDA) plant hardiness zone 5, according to the University of Connecticut. The plant prefers temperate climates with mild winters and warm summers. It is native to Japan and Korea, both of which have relatively cool, wet spring and fall weather, humid, warm summer weather and winters with relatively low amounts of snowfall.
Japanese honeysuckle is known to exist with invasive tendencies in 26 states, most of which are in the eastern half of the United States, according to IPSAWG. It is limited to those states that do not have very cold winters, as the plant cannot tolerate continual hard freezes. Japanese honeysuckle also needs plenty of rainfall to grow well, so it is not found in many desert states of the West.
Lonicera japonica thrives in full sun or partial shade. Although it prefers rich, moist soils, it can adapt to most other types of soils and growing conditions, according to the University of Connecticut. For that reason, it is very easy to grow. If cultivated by home gardeners, however, Japanese honeysuckle should be kept container-bound or rigorously controlled by careful pruning and pulling in order to prevent the vine from spreading.
Japanese honeysuckle is often found growing along roadsides, fields and banks, especially in wet areas such as along streams. The plant is so hardy that it will thrive even in very nutrient-poor soils and other areas where most plants cannot grow well. For that reason, it is often found growing in urban areas, such as highway medians, where polluted soil and air limit the growth of other plants. Some are also cultivated as ornamental plants. One cultivar in particular, “Purpurea,” has deep, greenish-purple leaves and reddish flowers. This variety of Japanese honeysuckle, although no less invasive than the species, is commonly offered for sale by some garden centers, according to the University of Connecticut.
Control measures can be used if you have Japanese honeysuckle overtaking desirable plants in your immediate environment. Hand-pulling the vines out of the ground can be effective in removing smaller plants. Mowing down the runners can control the spread of the vine, keeping it from crawling over nearby plants and structures, but the remaining plant will grow bushier. Controlled burning of the plant is usually effective in keeping it from spreading for at least two years, according to IPSAWG. A glyphosate herbicide is also effective if applied correctly in late autumn. Apply at 5 to 8 percent potency with a spray applicator, and completely cover the plant. Take note, however, that this use of a broadleaf herbicide may kill desirable plants nearby.