Landscaping woes? Here’s how to stop crabgrass in its tracks

Having a picture-perfect carpet of green grass in your yard is difficult, as weeds, insects and diseases are lurking.

Spring is time for yard work. Living in the day of COVID-19 is challenging. Fresh air and getting out into the yard is good for the body and mind. Just remember to keep your physical distancing, but gardening is a perfect pastime.

Now is the time to stop crabgrass before it starts.

Halt crabgrass and other grassy weeds from taking over your lawn by using herbicides called preventers or pre-emergents. These products work by preventing the germinating seed from establishing in the soil before it emerges. Preventers are only effective if applied and work their way into the soil prior to the weeds taking root.

It’s all in the timing

Crabgrass germinates in the early spring as the soil temperature increases. The sprouts shoot up when the soil reaches between 54 to 64 degrees 1-inch deep. Let’s face it, few people will monitor soil temperature, so there must be an easier way to know. The Kansas Mesonet weather reporting system has a station in west Olathe. About a week ago, the soil temperature was 48 degrees, below the threshold for germination.

Luckily there is a much simpler method. Redbud trees flower around the same time crabgrass germinates. Purchase the crabgrass preventer and be ready to apply when the redbud bursts into bloom.

How to improve effectiveness

Water crabgrass controls to activate. I like to put down the application in the spring when rainfall is predicted. Nature’s water is free and involves less work on my part. Applying on the early side is better than waiting too long and risking early germination.

There are several chemicals labeled in products available on the market. Active ingredients with the longest period of control are dithiopyr (Dimension) or prodiamine (Barricade).

Many pre-emergents are combined with fertilizer. Early spring fertilization is not recommended as it pushes top growth, resulting in more frequent mowing. Ideally, these products would be applied without the fertilizer. It is difficult to find preventers on the market without the addition of fertilizer. Why? These companies know homeowners crave to see a lush green lawn. Never mind it that means more mowing.

Remember to sweep or blow the pellets of preventer and fertilizer back onto the lawn and off driveways and sidewalks. If left on hard surfaces, they end up in our waterways and decrease our water qual

Do I need them?

There is an increasing movement to reduce pesticide and fertilizer use in lawns. Not everyone desires the lawn of green carpet, and more people are OK with a few weeds. Like any weed, crabgrass is opportunistic. The best defense for weeds is a thick lawn as the seeds need sunlight to germinate. This is why proper mowing and timely fall fertilization are keys to success.

Skipping an application may result in a summer of weeds, but if you can tolerate it, do without the application. Crabgrass thrives in full sun, so shady lawns can get by without an application.

A compromise might be the solution. Treat sunny areas and high-pressure areas along walks, drives and edging. The overall amount of chemicals will be reduced while keeping grassy weeds at bay.

Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Have a question for him or other university extension experts? Email them to garden.help@jocogov.org.