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Controlling Creeping Charlie

August 1, 2001
So creeping Charlie has aggressively crept into your lawn or landscape and is threatening to take over the entire neighborhood? Your plants are being crowded and smothered by it. It has gone too far. This means war upon his “kingdom.” What do you do?

Well, first of all, you need to be sure that King Charlie is who he says he is because proper weed ID is essential to good weed control. Creeping Charlie or ground ivy (Glechoma hederacea) is a perennial weed that spreads by seeds, rhizomes, and creeping stems that root at the nodes. The leaves are round or kidney-shaped, bright green, hairy, and opposite with scalloped leaf edges. The flowers are small, purplish blue, and funnel-shaped. It is a type of mint, so it has square (four-sided) stems; and when the plant is crushed, a strong mintlike odor is emitted.

If indeed you have creeping Charlie, you now need to ask yourself what is so appealing about this location, besides the fact that your garden is truly lovely? Chances are, it has the right conditions for optimum growth--shade, good fertility, and plenty of moisture. Life is even easier for creeping Charlie if there is no competition from other plants. You need to realize that this weed is persistent and may keep returning to the same area as long as conditions are favorable. No fear, maybe you can adjust the conditions. If possible, improve soil drainage or water less frequently. If the area is bare soil, it’s a good idea to plant something that competes well with weeds. Choose plants that are also well suited for these growing conditions, such as vinca, English ivy, pachysandra, or hosta. If the area is struggling turf, adjust your cultural practices to improve turf health and density (that is, increase mowing height to 3 inches or more, fertilize and overseed in the fall, water properly, etc.). Proper turfgrass selection is also essential for obtaining thick, healthy turf. Finally, shady areas may be brightened with a little pruning. Be aware that although shade is preferred, creeping Charlie has been known to move into full-sun areas.

Now that you’ve done your homework and you are familiar with your new neighbor, Charlie, how do you go about evicting him? Hand-pulling seems to work well as a quick, short-term fix. Be sure to remove uprooted plants to prevent re-rooting. Unfortunately, the extensive root system of rhizomes is very difficult to completely remove by hand-pulling. This means the wrath of creeping Charlie soon returns!

You may have heard that 20-Mule Team Borax (yes, the laundry soap) can be used to control creeping Charlie. Sodium tetraborate (borax) is a naturally occuring mineral, and they sell it at your local market. This sounds simple, but is it really a good idea? Borax has its advantages, but they seem to be outweighed by the disadvantages. Limited research has shown inconsistent results. Studies at Iowa State University (ISU) showed that Borax reduced a creeping Charlie infestation in turfgrass, but results were weather-dependent. Studies in Wisconsin, however, showed Borax was not an effective control of this weed due to soil conditions. ISU studies also found that borax can injure turf and other plants as well, causing stunting and yellowing.

There is little room for error with borax applications: Too little results in poor control, and too much results in injury to surrounding plants. Yet, there are a variety of “recipes” out there depending on who you ask--all of them swearing that you must follow the recipe exactly.

How does borax work? It contains boron, which plants need in minute quantities for healthy growth. However, larger quantities can have a toxic effect. Creeping Charlie happens to be extremely sensitive to boron. If boron quantities are sufficient, any vegetation can be killed. However, the availability of boron in the soil depends on soil type and pH. These factors affect the outcome of applying borax, as in the Wisconsin trials. No recipes I’ve found mention these important factors. Another problem with using borax is that boron does not break down or dissipate as conventional weed killers do, so repeated or excessive applications can result in bare areas where no vegetation can grow. This does not make for a lovely garden!

One final reason not to use borax is that it is not a registered pesticide. If you’ve heard of using vinegar for weed control, the same applies here. Although borax may sound like a “natural” weed-control method, it is important to remember that it may still be harmful to children and pets. Mixtures should be kept out of their reach. 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.

What is a better method of control for creeping Charlie? A postemergence broadleaf weed killer containing salt of dicamba (3,6-dichloro-o-anisic acid) is your best bet. Check the ingredient list on the label to see if it contains this active ingredient. Often it is found in combination products (Trimec, Three Way Lawn Weed Killer, etc.) and is mixed with weed killers, 2,4-D (2,4 dichlorophenoxyacetic acid) and mecoprop or MCPP (2-(2-methyl-4-chlorophenoxy) propionic acid). Products containing triclopyr or 2,4-DP may also provide decent control. Another option is Confront (triclopyr + clopyralid), which has also shown effective control but must be applied by professional applicators. Preemergence products do not control creeping Charlie.

Now I didn’t mean to get your hopes up. Realize that these specific herbicides cannot be used in every situation or area such as vegetable or flower gardens as many broadleaf plants are very susceptible to these herbicides. If even a small amount drifts onto certain plants, severe injury can result. It’s enough to make your rose’s leaves curl! Literally. In these areas, hand-pulling or hoeing is your best bet. It is helpful to keep borders clean so you can easily see and control invading weeds. These herbicides can, however, be used on turf; but you will want to consult the product label first. With any pesticide, always read and follow label directions. The label is your best source of application information.

Herbicide applications work best when weeds are actively growing. Timing is important as well. Mid- to late autumn is an excellent time to apply herbicides to creeping Charlie and other perennial broadleaf weeds like dandelion. During October and November, Charlie is busy preparing for winter by sending food reserves down to his roots. A herbicide that moves within a plant moves down to the roots as well. This is just where we want it to be! For best results, a second application should be applied 3 to 4 weeks later.

If Charlie rears his ugly head again in the spring, spray him again. In fact, wait until he is blooming, as he is very susceptible to herbicides at that time (April to June). Again, a second application may be necessary.

Before you spray, check weather conditions. Best results are achieved when temperatures are in the mid 60s to low 80s and there is no rain for 24 hours following application. Don’t spray when conditions are too windy (to avoid injuring desirable plants with herbicide drift). If the area is turf, don’t mow for a few days before and after application. Also, check the label before reseeding to see if there is a waiting period.

Good luck with your war on Charlie! He is a very difficult weed to control. You may decide to make peace and be neighbors with Charlie. You could have worse neighbors.

Author: Michelle Wiesbrook


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