How do I get rid of Creeping Charlie without illegal weed killer?
Thank you for contacting the Toronto Master Gardeners. As you probably know Creeping Charlie is a very common weed in southern Ontario and a very difficult weed to control. The reason it is so challenging is the way it spreads, both by seed and (primarily) by creeping stems which root at each leaf node so that it forms dense mats. Leaving even a tiny piece of a root behind when hand pulling this weed will enable it continue its aggressive growth. So there is no easy solution for getting rid of it, unfortunately, but there are some things that you can do to get it under control.
As with any grass weed, the presence of Creeping Charlie is an indicator of problems with your lawn. These problems include compacted soil (aerate your lawn well once a year, usually in the spring), low calcium and acidic soil (add lime), and low organic matter (top-dress your lawn with compost and organic fertilizer).
Creeping Charlie prefers shady spots, so plant these areas with either shade tolerant turfgrass or other groundcover, or a thick layer of mulch to keep Creeping Charlie from taking hold there.
Healthy grass will crowd out weeds, so use good cultural practices in maintaining your lawn : mow at a high level (2.5 to 3 inches), water deeply and infrequently, reseed bare patches and overseed in the spring and fall. Here is a link from Landscape Ontario with helpful information about maintaining a healthy lawn :
Unless your lawn is heavily infested with Creeping Charlie, try removing the plants by hand, after a rainfall or watering. Try to get the whole plant without breaking it, and keep doing this until no more shoots come up. Without green leaves to photosynthesize and produce new energy, the plant will no longer be able to send up new shoots, and the energy stored in the rhizomes will be exhausted and they will eventually rot away. If you have larger mats of weeds, try smothering them with newspaper. Dispose of the plants so that they cannot reseed, so not in your compost.
The best time to attack Creeping Charlie is in the early spring. Mow the grass close to the ground to remove it. You could consider applying corn gluten meal which is an organic pre-emergent herbicide. It does not prevent weeds from germinating but does prevent root formation, so the timing of application is critical. Here are a couple of websites with information about corn gluten :
Ultimately, the only sure way to control Creeping Charlie is by removing the top layer of soil that contains the roots and seeds. This can be done with soil solarization, which essentially is covering the soil in thick plastic during the hot summer months to kill the weeds. Here is a link to a previous question about solarization that was sent to the Toronto Master Gardeners :
Best of luck getting rid of Creeping Charlie in your lawn !