Crabgrass in the Summer | Everything You Need to Know

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May 8, 2020

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Summertime is near, and it’s time to ramp up for lawn care during the warmest months of the year, including weed control. One weed that’s the bane of every homeowner’s existence in the summer is crabgrass.

This unsightly, grass-like weed can quickly take over your yard due to its ability to blend in from a distance. Next thing you know, your yard is filled with thick, clumpy growths that overrun and choke out your beautiful turf.

Below, we’ll show you how to conquer crabgrass in the summer through various methods. All you have to do is choose the method that suits you and get to work.

What is Crabgrass and How to Identify It?

Crabgrass in the Summer | Everything You Need to Know 1

Crabgrass is an annual weed that crops up when soil temperatures stabilize at 55-65 degrees F, which generally occurs in the late spring or early summer. A crabgrass plant can produce a whopping 150,000 seeds during its peak season, allowing it to spread with relative ease.

Identifying crabgrass can be a little difficult, as it can blend in with other grasses from a distance. It also adapts to its surroundings and environment, making it even harder to identify.

In its seedling phase is when crabgrass stands out the most, as its blades are a quarter-inch or wider — most grasses are far thinner when sprouting. The seedling also starts developing side shoots that grow outward as separate branches of the plant.

Once it reaches its mature phase, crabgrass can take on many colors, so it’s difficult to identify based on this. In its mature phase crabgrass stands out upon closer inspection due to its wider blades than most turf. Its blades also have distinct creases down the center, and the blades tend to grow from several areas on the stem instead of from a central point.

Depending on the species, crabgrass stems can be small (1-6 inches) and smooth or long (12-48 inches) and hairy.

As it continues to grow, crabgrass will put out stolons or runners to take over new areas. This is a trait similar to St. Augustine grass. Unlike the turfgrass, which has stolons that are virtually endless, crabgrass runners rarely extend beyond 1-2 feet.

Crabgrass further stands out in the days after mowing, as it grows quicker than most grasses, creating unkempt-looking clumps.

How to Control Crabgrass

Though it can quickly overtake a lawn due to its prolific seeding, crabgrass is relatively easy to control in the summer culturally or with post-emergent herbicides. Since crabgrass germinates in the late winter and through spring, there is no summertime pre-emergent crabgrass control.

Controlling Crabgrass Without Chemicals

Natural crabgrass control comes in two forms, cultural control and natural remedies. Cultural control is preventing crabgrass growth by creating a poor growing environment, whereas natural control is killing the weed without harmful chemicals.

Cultural Crabgrass Control

Crabgrass spreads via seeding so the best way to keep it from continuing its spread is to prevent its seeds from ever developing into sprouts. A great way to do this is with a thick, healthy lawn, as this blocks the sun from reaching the seedling, eliminating any chance of it growing.

You can achieve this vigorous lawn through proper fertilization and irrigation, and by mowing at the recommended height. If your turf is a little on the thin side, you may also consider overseeding to fill it out.

Natural Crabgrass Control

There are several natural and organic herbicides on the market that claim to tame crabgrass issues, but the best way to tackle it in your lawn is manual removal.

Before the crabgrass matures and starts dropping seeds, trace its runners back to the main stem. Use a small spade or your fingers to loosen the soil around the crabgrass plant, then grip the base of the stem and pull upward sharply to dislodge the plant and its roots.

Once you pull the plant, immediately place it in a bucket or trash bag and dispose of it.

Post-Emergent Crabgrass Control

Chemical herbicides are also quite effective at killing existing crabgrass. There are pre-emergent herbicides for crabgrass, but they are largely ineffective in the summer because the seeds germinate in the late winter and through spring.

Natural Crabgrass Control

To kill existing crabgrass, there’s a number of effective post-emergent herbicides on the market, but you must choose the one that suits your situation best.

If you’re controlling existing crabgrass in turf, you can use any product containing the active ingredient quinclorac. Some crabgrass species have developed a tolerance to this chemical, so it may take several applications to be fully effective. Dithiopyr is another option, but this is only available for professional use.

If you have crabgrass issues in an ornamental plant bed, you can also try products with the active ingredient fluazifop or sethoxydim.

Post-emergent crabgrass control works best when the crabgrass is young — in its one- to-three-leaf phase — and may require additional treatments to control mature plants.

Conquer the Crabgrass

Armed with the knowledge of how to identify and kill crabgrass, you’re ready to prevent your lawn from being overrun by this invasive weed. The only decision now is whether you prefer the more hands-on natural route or the quicker action chemical control offers.

No matter what route you choose, you’re now prepared to conquer crabgrass this summer.