Jingjing Yin, Commercial Ornamental Horticulture
Cornell Cooperative Extension
Capital Area Agriculture and Horticulture Program
Glechoma hederacea, also known as creeping Charlie, ground ivy, creeping Jenny, or gill-in-the-ground, is a perennial herb in the mint family. It spreads by seeds, rhizomes, and creeping stems to form a dense mat in lawns and gardens, especially in damp and shady areas. It will spread out into sunny areas of a lawn as well. It has rounded leaves with toothed margins. It is an early spring bloomer that is easily recognized by its small, violet flowers. Once established in a lawn or in a garden, creeping Charlie can suppress the growth of surrounding plants due to a characteristic called “allelopathy” which means the plant will release biochemical compounds to inhibit the development of neighboring plants. Studies have found that flowers growing alongside creeping Charlie experienced decreased seed germination rate.
When creeping Charlie is present in low numbers, hand weeding multiple times during the season would be effective. Just make sure to remove the roots as well as the aboveground portion of the plants. If your lawn is heavily infested by creeping Charlie, a dethatching tool or a sod-cutter can be used to remove the weeds. These tools can cut out some of the grasses as well, so you need to reseed after dethatching or sod removal. Another option to remove creeping Charlie in an area less than ¼ of an acre is through solarization. Solarization involves placing a clear plastic sheet over the soil during the warm months of spring and summer. The clear plastic sheet captures sunlight and creates high temperatures underneath it where grasses and weeds cannot survive. Solarization requires sunny days. In a cooler and shaded area, the process would take 5-6 months or even a full year.
Applying postemergence broadleaf herbicides is another option for controlling creeping Charlie. The best choice for homeowners is a weed killer that contains triclopyr. This active ingredient is found in many commercially available homeowner lawn care products, oftentimes in combination with other herbicides such as dicamba (3,6-dichloro-o-anisic acid), 2,4-D (2, 4 dichlorophenoxyacetic acid) and mecoprop or MCPP [2-(2- methly-4-chlorophenoxy) propionic acid]. Products containing 2,4-DP can also provide adequate control. All of the products listed above can be used for treating lawns, but cannot be used in vegetable or flower gardens as many common vegetables and ornamentals are broadleaf plants that are very susceptible to these herbicides. When using an herbicide for creeping Charlie control, be sure to read and follow all label instructions of the product that you select to ensure that you use the product in the safest and most effective manner possible.
If you and your neighbors don’t mind creeping Charlie growing, they can be a good nectar source for bees, such as sweat bees, bumble bees, and honey bees. However, if you are trying to create a pollinator friendly garden or lawn, it is not a good idea to let creeping Charlie take over the garden/lawn. Bees need a variety of food sources, but creeping Charlie is invasive and can prevent other flowers from establishing. Also creeping Charlie does not have pollen readily available for bees and other insect pollinators. In addition, creeping Charlie flowers have an interesting strategy for pollinators. Studies have found that only 8% of the flowers had a large volume of nectar and the rest of the flowers provided almost none. The availability of nectar also varies throughout the day. Most flowers produce their nectar at night or in the early morning, and do not replenish their nectar throughout the day.
References:
Controlling Creeping Charlie. Division of Extension, University of Wisconsin-Madison: https://hort.extension.wisc.edu/articles/controlling-creeping-charlie/
Creeping Charlie: Management and value to pollinators. Turfgrass Science, University of Minnesota: https://turf.umn.edu/news/creeping-charlie-management-and-value-pollinators