The University of Iowa developed a formula for treating creeping Charlie using Borax (20 Mule Team Borax found with other laundry detergents in the grocery). Creeping Charlie is extremely sensitive to high levels of boron (found in Borax). While grass is relatively tolerant of boron, you should not repeat this application, or it may kill the grass. Here is the formula as it was released:
One time only!
2-5 teaspoons Borax / 1 quart warm water* / 25 square feet (an area 5’ X 5’ square)
*Because it is difficult to spread 1 quart of solution over that area, a gallon of water can be substituted, if you make sure you still spread that same amount of borax over the same area. This should be applied through a sprinkling can. It cannot be concentrated, since it will clog up most sprayers. Be sure to spread this solution over 25 square feet. Try it first with water to get a feel for how to spread it accurately. Allow the solution to dry on the foliage for 24 hours. Some areas of the United States have naturally higher levels of boron in the soil. In those areas, the lower dosage is needed. In our area, the higher dosage is being used. It causes a little yellowing of the grass, but seems to do no permanent damage. Be careful not to apply this formula to anything else. Perennials, shrubs and other plants may be sensitive too. Borax does not kill the creeping Charlie quickly, but you should see damage within a week or two. Over the next several weeks, more and more of the creeping Charlie will weaken and die. Many people are using this method of minimizing the creeping Charlie throughout the summer, finishing it off in fall with weed free zone. That way you use less 2,4-D.
material.
