Timing is important when it comes to controlling crabgrass in the lawn. This nuisance grassy weed is fairly easy to prevent but trickier to stop once up and growing, which is why the best strategy is to stay a step ahead of it.

What is crabgrass?

Crabgrass is an annual weed that sprouts when the soil warms in spring. It sends out its skinny, green, ground-hugging mats in spring and then produces copious amounts of seeds in mid to late summer. When cold weather hits, growth will stop, but the dropped seeds are viable and able to re-infest your lawn for the next few years.

When is the best time to prevent crabgrass?

Most crabgrass preventers work best when they’re applied and watered in right before crabgrass seeds start germinating in the spring. Wait too long, and the crabgrass is up and growing, rendering the product nearly useless. Apply too early, and later-germinating crabgrass might continue to pop up after the preventer has broken down. In general, you’ll know when you mow! If your lawn is actively growing, your weeds are too. Apply after the 2nd or 3rd mowing for maximum effectiveness in stopping crabgrass.

Depending on the climate, crabgrass germinates as early as mid-January in warm areas to as late as mid to late May in colder, northern regions. One way to widen the effectiveness window is to go with a crabgrass preventer that not only stops the germination of crabgrass but kills young crabgrass plants in their early stage.

What can I use to prevent crabgrass?

GreenView Fairway Formula Spring Fertilizer with Crabgrass Preventer provides pre-emergent control of over 40 common weeds, including crabgrass, chickweed, foxtail, henbit, and many more. It also provides post-emergent crabgrass control for up to 4 weeks after it germinates, meaning if you’re late to apply the product, you will still be able to stop seedlings that have sprouted. Extended time-released nitrogen also greens your lawn into summer without excess growth.

What if I am too late to apply a crabgrass preventer?

Killing crabgrass later in the growing season is possible, but that requires using two and sometimes three applications of an herbicide that specifically targets nuisance grasses.  Digging out crabgrass plants is another option, but that can be daunting in widespread infestations. In the long run, growing a dense, healthy lawn is as good of a crabgrass strategy as anything. With thick turfgrass in place, there’s little room for any weeds to elbow their way in -- crabgrass or otherwise.

Three good lawn-encouraging tactics to follow include:

  1. Cut the grass regularly and on a high setting. Crabgrass is much more common in “scalped” lawns than where taller blades shade the ground.
  2. Pay attention to soil nutrition. Turfgrass better competes with crabgrass in loose, rich soil that has adequate nutrients. Test your soil to see where you stand, then get on a regimen to supply your soil with the regular nitrogen and other nutrients it needs to maximize growth.
  3. Overseed. This means adding new grass seed to help the lawn thicken and fill in any bare spots where opportunists such as crabgrass grow. Fall is a good time to seed, reseed or overseed, using good-quality seed varieties formulated for your soil type, sun exposure, and climate.