Extension Educator, Horticulture
I'd be a rich woman if I could devise a marketable way to control Japanese beetles, moles, creeping Charlie and people who don't use their car turn signals. Creeping Charlie control is probably one of the most common questions.
First, get proper weed identification. Creeping Charlie, Glechoma hederacea, also known ground ivy indeed creeps with long stems that root at the leaf nodes. The perennial plants have kidney bean-shaped leaves with scalloped leaf margins and small purplish blue flowers.
If creeping Charlie is in the lawn, consider why Charlie is growing and the lawn isn't. Often it is in areas too shady for grass. Consider improving lawn management techniques, selective tree pruning to allow more sun or choose plants that grow well in shade. Any open areas in lawns or gardens invite weeds so use mulch or other ground covers to help fill in the areas. Similar to many weeds, creeping Charlie will tolerate a wide variety of soils and environmental conditions.
Success in controlling creeping Charlie is in managing the original plant before it sets seed through hoeing, hand removal, smothering with mulches and/or herbicides. With hand pulling try to remove as much of the root as possible and be vigilant. Or think of Charlie as a nice green ground cover.
What about borax to control creeping Charlie? Michelle Wiesbrook, U of I Extension specialist shared the following information in a past Home, Yard and Garden Newsletter .
"Sodium tetraborate (borax) is a naturally occurring mineral, and is sold at the local market in the laundry soap aisle as 20-Mule Team Borax. Any advantages with Borax seem to be outweighed by its disadvantages. Limited research has shown inconsistent results. Studies at Iowa State University showed that Borax reduced creeping Charlie infestation in turfgrass, but results were weather-dependent and it caused stunting and yellowing injury in turf and other plants. Studies in Wisconsin, however, showed Borax was not an effective control of this weed due to soil conditions."
Wiesbrook notes, "There is little room for error with borax applications: Too little results in poor control, and too much results in injury to surrounding plants."
"Borax contains boron, which plants need in minute quantities for healthy growth. However, larger quantities can be toxic. Creeping Charlie is extremely sensitive to boron. The availability of boron in the soil, however, depends on soil type and pH. Another problem is boron does not break down as conventional weed killers do, so repeated or excessive applications can result in bare areas where no vegetation can grow."
"One final reason not to use borax is that it is not a registered pesticide. Although borax may sound like a "natural" weed-control method, even natural products can harm children and pets. Registered pesticides have been studied extensively and come with labels that tell you how to protect yourself and others. The borax box tells you how to wash your clothes."
According to Wiesbrook a better control method for creeping Charlie in your lawn is a postemergence broadleaf weed killer containing dicamba often found mixed with other weed killers, 2,4-D and mecoprop or MCPP in combination products (Trimec, Three Way Lawn Weed Killer, etc.) Products containing triclopyr or 2,4-DP may also provide decent control. A second application later in the season according to label direction can provide additional control.
Remember herbicides cannot be used in every area such as vegetable or flower gardens. Herbicides can injure desirable plants through application or drift if not used properly. With any pesticide, always read and follow label directions. Herbicide applications work best when weeds are actively growing. Creeping Charlie is very susceptible to herbicides when it is in flower (April to June).