Controlling
Creeping Charlie
Creeping Charlie, ground ivy, gill-on-the-ground, creeping Jenny –
it doesn't matter what name you call it, this is a weed that's difficult to
control. Glechoma hederacea is a perennial weed in the mint
family that spreads by seeds, rhizomes and creeping stems that root at the
nodes. This European native was introduced to North America by early settlers
who thought it was a good groundcover for shade. The bright green, round or
kidney-shaped leaves have scalloped edges and are produced opposite each other
on the square (four-sided) stem. In spring small, bluish-purple, funnel-shaped
flowers bloom on short stems. When the plant is crushed, it produces a strong
mint-like odor.
Creeping Charlie thrives in moist, shady spots such as under trees and
shrubs. If you can alter these conditions, it will be easier to discourage this
weed. If possible, improve soil drainage or water less frequently, or prune
trees up so the area receives more light. If the area is weak or the lawn thin,
try to improve turf health and density by increasing mowing height to 3 inches
or more, fertilizing as appropriate for the grass type, overseeding in the fall, and watering
properly. Also, make sure you're growing the most suitable type of turfgrass for
the area (shade tolerant varieties under trees). Or consider removing the grass
and growing shade-loving plants that compete well with weeds, such as vinca, English ivy,
pachysandra or hosta.
You can hand-pull creeping Charlie, but it's difficult to completely remove
the extensive
creeping stem system so this may not be a viable solution if the area is heavily
infested. Make sure to
remove the plants you've pulled so they can't re-root. A dethatching tool, also
called a power rake or vertical mower, can be used to clean up larger areas of
creeping Charlie-infested lawn. This tool makes small cuts in the soil and the
roots so you can "comb out" the creeping Charlie with a rake. This cuts out some
of the grass as well, so you may need to reseed after dethatching. The best time
to do this is mid-August to mid-September, which is also the best time to reseed
your lawn.
Borax has been touted as an organic control for creeping Charlie, but
research at both the University of Wisconsin and Iowa State University has shown
that borax is typically not very effective and can injure turf and other plants
as well, causing stunting and yellowing. Borax contains boron, which is
necessary in very small amounts for plant growth but is toxic in larger doses.
Creeping Charlie happens to be extremely sensitive to boron, so supplying more
boron should be detrimental to it more than other plants, such as grass, that
aren't as sensitive. However, since boron availability in the soil depends on
soil type and pH, it's difficult to determine just how much boron should be
applied in any one place. And there's little room for error: too little results
in poor control and too much injures surrounding plants. Also, boron doesn't
break down or dissipate in the soil, so repeated or excessive applications can
result in bare areas where no vegetation can grow.
The best means of controlling creeping Charlie is with a postemergence
broadleaf herbicide. As with any pesticide, always read and follow label
directions. The best choice for homeowners is a weed killer containing salt of dicamba
(3, 6-dichloro-o-anisic acid). This active ingredient is often found in
combination products, such as Trimec or Three Way Lawn Weed Killer, so check the
ingredient list on the label to see if it contains dicamba. The other chemicals
in these combinations are generally 2,4-D (2, 4 dichlorophenoxyacetic acid) and
mecoprop or MCPP (2-(2-methly-4-chlorophenoxy) propionic acid). Products
containing triclopyr or 2,4-DP may also provide decent control. These products are good for applications on lawns, but
can't be used in vegetable or flower gardens as many broadleaf plants are very
susceptible to these herbicides and even minimal amounts of the herbicide will
cause severe injury. In those areas it's best to hand pull or hoe the invaders.
If there's more creeping Charlie than grass in your lawn, it may be easier to
start over by killing all the vegetation and reseeding the lawn.
Herbicide applications should be made when the weeds are actively growing.
Mid to late autumn, after the first frost, is an excellent time to apply
herbicides to creeping Charlie and other perennial broadleaf weeds. At this time
the plants are busily sending food reserves to the roots, so the herbicide is
moved down to the roots as well, resulting in better control. Make a second
application 3 to 4 weeks later for best results. Applications can be made again
the following spring, but wait until the plants are in bloom (April to June) as
the plants are most susceptible to herbicides then. Again, a second application
may be necessary.
For best results make applications when temperatures are in the mid 60s to
low 80s, there is no rain expected for 24 hours following application, and there
is little or no wind. When applying herbicides to lawns, don't mow the area for
a few days before and after application.
Controlling creeping Charlie takes some work and is frequently not totally
successful. Herbicide applications may be needed on a regular basis for many
years to completely eliminate the weed. It may be easier to just learn to live
with it, and periodically knock back the weed when it becomes too dense.
– Susan Mahr, Department of Horticulture
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