Cultivated honeysuckle is a prized plant to have in gardens and landscapes. The blooms are sweet-smelling, and their berries in late summer and early fall attract birds and other wildlife. Not all varieties of honeysuckle are desirable to have in your landscape, though. Japanese honeysuckle, also known as bush honeysuckle, exotic honeysuckle, or Lonicera japonica as its scientific name, is an aggressive and invasive weed that can quickly take over a lawn, garden, or landscape. In many states, it is categorized as a noxious weed, and the sale of seeds are prohibited because of the environmental damage they cause.
As the cousin of cultivated honeysuckle, there are many similar properties. One of the biggest identifying factors is the hollow stems of Japanese honeysuckle. Japanese honeysuckle produces white flowers from May into June. Flowers will then turn a creamy yellow as they age. The berries of the Japanese honeysuckle are a deep purple color, while cultivated honeysuckle produces a bright orange or red berry. These weeds can grow upwards of 6 feet tall. Their roots are generally shallow, but they have traveling rhizomes that can spread far underground, which is part of what makes them so difficult to control. Leaves are oval-shaped and are smooth and dark green on top and light green with hairy veins on the underside. Flowers bloom in symmetrical pairs on either side of stems.
Japanese honeysuckle originated in east Asia. It was brought to the United States in the late 1800s as an ornamental ground cover. It thrives in a variety of soils and climates and is now found in most states across the country. It is often found along riverbeds, lakes, floodplains, meadows, and forests. The plant quickly spreads through its rhizomes and will take over and strangle native plants and herbs and disrupts species diversity. It is one of the top 10 invasive plants in Georgia. In Florida, it is listed as a category 1 invasive plant. And in Kentucky, Tennesee, and South Carolina it is listed as a severe invasive threat.
The ability to tolerate moderate shade, many soil conditions, rapid growth rate, and the ability to outcompete other surrounding plants for sunlight is what makes this weed so dangerous. While its rhizomes help this noxious weed spread, it is also spread through birds and other wildlife eating the berries and excreting the seeds in other locations. It is a deciduous shrub, and seedlings will emerge in early spring. A single Japanese honeysuckle can spread up to 30 feet and cover fences, sheds, and other structures, and can overrun trees, other shrubs, or anything else in its path.
Keeping this weed under control can be extremely difficult and requires diligence to eradicate. Simply mowing them down won’t do much good, as they will form new growths from the remaining stems and roots. If discovered early enough, Japanese honeysuckle can be pulled out from the roots as they emerge in early spring. Larger, more established growths require a multi-step approach to control. Plants should be cut down in late summer, and cut ends should be spot treated with undiluted glyphosate. This must be done carefully, as glyphosate will kill any surrounding plants it touches. Proper lawn care and weed control practices will help ensure Japanese honeysuckle does not overrun your landscape. Catching growth early and removing it from the roots is the best possible means of preventing its spread.