Hello Mary -

You have several options to eradicate the creeping Charlie:

1. When creeping Charlie is present, but in low numbers, it may be possible to control the weed via hand weeding. When hand weeding, it is critical to remove the roots as well as the above ground portion of the plant to ensure that there is no re-emergence. Due to the aggressiveness of creeping Charlie, multiple weeding events may be required to remove all creeping Charlie vegetation.

2. If creeping Charlie has already overtaken a lawn, there are several options for eradication. A sod-cutter is a machine that typically removes sod for transplant into a new lawn, but can also be used to quickly remove strips of weeds, like creeping Charlie, from a lawn. Removing strips of creeping Charlie will create an area of bare soil within the lawn, so if a sod-cutter is the preferred method of removal for a homeowner, it is important that all creeping Charlie vegetation is eradicated to prevent re-invasion. If any piece of plant material is not removed, there is potential for creeping Charlie to re-establish within the lawn. After all creeping Charlie vegetation is removed, the areas of bare soil should be seeded with high quality turfgrass to ensure dense, uniform germination throughout the area. Lawns with dense turfgrass coverage are less susceptible to weed invasion, including invasion by creeping Charlie.

3. A second way to remove an area of a lawn overrun by creeping Charlie is through solarization. Solarization is a pesticide free form of weed control that involves placing a clear plastic sheet over the soil during the warm months of spring and summer. The clear plastic sheet captures heat and sunlight, raising soil temperatures to the point where grasses and weeds can no longer survive. Solarization is best fit for sunny, flat sites that are less than 1/4 of an acre in size. In cooler, shaded areas (where creeping Charlie is likely to be found) the process of solarization takes the better part of a growing season, typically 5-6 months, or up to a full year in some instances. Additional information on solarization can be found through the Xerces society. The plastic should be removed in the late fall when soil temperatures are 35-55°F so that new grass can be installed via dormant seeding. Dormant seeding occurs at these temperatures because the soil is too cold for germination to occur, but the ground is not yet frozen. This ensures that the target species seeded into the newly prepared area will germinate once the proper number of degree days has occurred. If seeded properly, the new turfgrass area should be dense, uniform, and free of weed pressure.

4. To combat creeping Charlie, it's been suggested that you can raise the soil pH to make it more alkaline. The claim is backed by the theory that by boosting the alkalinity of the soil, creeping Charlie cannot grow or thrive. The problem with this concept is that this plant, like most weeds, is adaptable to a range of soil conditions. In fact, it can thrive in soils that are mildly alkaline to mildly acidic, between 7.5 and 5 pH. This broad range is where most plants survive. The thing is, by adding amendments like lime to make the soil so alkaline that even weeds will not grow, it will also make it uninhabitable for your landscape plants.

For more info, see these links:
https://turf.umn.edu/news/creeping-charlie-management-and-value-pollinators
https://extension.illinois.edu/lawns/managing-creeping-charlie-lawns

Good luck!

On Wed, Jul 31, 2024 at 10:20 AM, Ask Extension

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