Treating aggressive perennial weeds requires proper timing, an effective product and cultural
practices to help deter re-establishment. Creeping Charlie (Glechoma hederacea) is consistently a problem weed though some homeowners have come to tolerate it because it attracts and provides food for pollinators (one of its few redeeming qualities).
|Creeping charlie in bloom|
Best cultural practices are recommended to encourage healthy growth and vigor of lawn grasses. Proper selection of grass varieties for the site, fertilization and watering practices that encourage deeply rooted plants are important to a healthy lawn that can out-compete weeds.
Most lawns are comprised Kentucky bluegrass and perennial ryegrass and require full sun, proper nutrition, and non-compacted soils for optimal growth. A soil test can provide recommendations for soil health and fertilizer. As shade increases, it becomes less and less favorable for sustaining a lawn in this area, and more favorable for weeds like creeping Charlie. Pruning to increase sunlight and aeration may be options for improving growing conditions; however, if the area is too shady, give up on trying to grow grass in this area and consider planting other ground covers or a shade garden of perennial flowers.
|Creeping charlie and dandelions are |
both perennials weeds in turf
Timing of herbicide treatment is key to successful control of perennial weeds like creeping charlie. As always, read and follow all instructions and guidelines on the label of any product, synthetic or organic, including proper clean up and storage. Note that herbicides are only effective in managing weeds if applied properly. The herbicide label is the law and misuse constitutes illegal application. Autumn is the best time of year for systemic herbicide applications when creeping charlie is actively taking up nutrients from the soil to sustain the plant through the winter. Spring is a second option when the plant is actively growing.
Some considerations for choosing an herbicide:
- If you have a large area of creeping charlie or if your lawn is more than 50% creeping charlie, you may want to consider killing off the entire area with glyphosate (the active ingredient in the non-selective herbicide Round-Up®) and re-seeding. Note this product kills all plants including lawn grasses. Depending on the product formula, re-seeding can occur within a few days after application. People and pets may re-enter the area when dry.
- If you want to treat small areas where creeping charlie is growing in lawn grasses, you can use a a selective herbicide like 2,4-D, Dicamba or triclopyr, or combinations of these products. Triclopyr will be the most effective option for creeping Charlie. These are systemic, selective broadleaf herbicides. They are taken up by the plant and kill the entire plant from roots to flowers. Note they do not kill lawn grasses if applied properly. These products are effective and usually require only 2-3 applications per year depending on proper use and timing.
- Chelated iron burns creeping charlie foliage and its stolons. A maximum of four applications may be applied annually. Lawn grasses may show some burning on the blades, but will recover. They also will turn a deep green due to the absorption of iron. Because of this, chelated iron should not be used for spot treatments as it will result in deep green spots throughout the lawn. Treated areas may be re-seeded the next day, and people and pets may re-enter the area when dry. Note that chelated iron can be expensive, and may stain equipment, sidewalks, driveways, etc. Here is a publication from the University of Maryland with more information
In the past, borax (boron) was a product recommended for eradicating creeping charlie. However, research has shown that the addition of boron to soil, even in very small amounts, can create an unfavorable growing environment, and make it difficult to re-establish lawn grass. Also, this is an illegal application. Any product used in this fashion must be specifically labeled for the weed you are trying to control. Therefore, borax it is no longer recommended for eradication of creeping charlie.
Going forward, regular and well-timed cultural lawn care practices will help keep weeds like creeping charlie managed and turfgrass healthy. The Upper Midwest Lawn Care calendar is a good tool for helping time applications of fertilizer and pre and post-emergent herbicides and when to perform tasks like aeration to reduce compaction. For more on healthy lawns: http://www.extension.umn.edu/garden/yard-garden/
Round-Up® is a trademark of Monsanto Corporation.