Timing is important when it comes to controlling crabgrass in the lawn. This 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.

What does crabgrass look like?

Crabgrass can reach up to 15 inches and is recognizable by its flat, green (or yellow/brown) mats that hug the ground. It thrives in areas with sparse soil and high sun exposure, like lawns and gardens. In mid-late summer, it produces a large number of seeds that can be spread by wind or animals and can remain viable to reinfest for several 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. If you wait too long, the crabgrass will begin growing and the crabgrass preventer might not be effective at all. Apply too early, and later-germinating crabgrass might continue to pop up after the preventer has broken down.

In general, you’ll know to apply when you begin mowing because if your grass is growing, the 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 crabgrass and over 40 common broadleaf weeds, including 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 fertilizer 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 time-consuming 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 care tactics to follow:

  • Cut the grass on a high setting regularly. Crabgrass is much more common in shorter lawns than where taller ones where grass blades shade the ground.
  • 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.
  • 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.