It’s that time of year when the fresh green grass begins to emerge in homeowners’ yards, signifying the spring is here to stay. But grass doesn’t always make its debut alone—sometimes crabgrass threatens to steal the spotlight. After hiding in the soil all winter long, this course, yellow weed can begin to sprout and damper the look and feel of your lawn. Learn how to prevent and control this unappealing grass so your yard is looking pristine for the summer.
First and foremost, a healthy lawn is the number one defense against crabgrass since unwanted weeds can’t get the necessary footing to thrive in a cared for, vibrant lawn. These are the most important lawn care guidelines to keep crabgrass from becoming a problem:
- Mow at frequent intervals to keep grass at a consistent and correct length. Depending on your type of grass, there may be different recommended mowing lengths. It’s important to have your grass at the correct length because crabgrass requires plenty of light to germinate, so keep the grass as thick and long as possible to create shade near the soil surface. Cutting your lawn too close produces patches where crabgrass and other weeds can germinate.
- Remove no more than one-third of the grass blade at one time when mowing. Removing more not only allows more light to reach weeds, it also can injure the grass.
- When watering your lawn do it in long, heavy intervals rather than shallow, frequent ones. Watering on an irregular schedule and only when needed promotes deeper root growth that creates ideal growing conditions for crabgrass. Remember that most established lawns require about one inch of water per week from rain or irrigation. If your lawn is newly-seeded, water in shallow, more frequent intervals until the grass gets established.
- Fertilization of your lawn at least once of year is key to a healthy lawn.
Controlling crabgrass if you already have it
Prevention is one thing but if crabgrass is already an issue in your lawn, proper maintenance alone may not be enough. We recommend a pre-emergent herbicide as the next plan of attack. A pre-emergent herbicide is a solution that works by by killing the crabgrass seedlings as they germinate. When applying the pre-emergent herbicide, always follow the manufacturer's directions. Additional tips we recommend are:
- Be aware that timing is essential when using pre-emergent herbicides. Depending on weather patterns, application of the herbicide can vary greatly. For example, because we have experienced in Minnesota a warmer than usual winter, applying pre-emergent herbicide earlier than usual is recommended.
- Apply the herbicide when the ground temperate is above 60 degrees. Obviously, we are proposing you monitor your soil temperature, however, when you notice shrubs blooming and trees budding, that means it’s time to apply the herbicide. For newly seeded lawns, wait until you have mowed your lawn three times before applying the herbicide to avoid killing the new grass seedlings.
- Apply the herbicide uniformly across your lawn. If you miss a spot, crabgrass can get established and then spread to the rest of your lawn.
- Do not de-thatch or aerate the lawn after applying the herbicide. Doing so may break the chemical barrier of the herbicide.
- Wait two to four months to re-seed the lawn after using a pre-emergent herbicide.
- Do not use a pre-emergent herbicide if crabgrass is already in the lawn or if you have just installed sod.
One thing to note: if the crabgrass seeds have already sprouted and crabgrass has appeared in your grass, the pre-emergent herbicide will do no good. No fear, post-emergent herbicide products can go a long way in controlling crabgrass if it has already germinated. Post-emergent herbicides work by killing the crabgrass plants. Apply these herbicides only to the crabgrass that is visible and read all the instructions carefully.