When to Apply Crabgrass Preventer in Illinois

pre-emergent crabgrass preventer
In this post, we’ll discuss crabgrass, when it emerges, and when to apply pre-emergent crabgrass killer in Illinois so you can keep it at bay.
One of the biggest enemies of a healthy lawn is crabgrass. Besides maybe dandelions, there is no more pervasive weed that invades homeowner’s lawns.

About Crabgrass

identifying crabgrass photoCrabgrass gets its name from its very crab-like appearance.
It is typically easy to identify from its growth pattern, with the grass blades of the plant shooting out of the ground from a single
Crabgrass is an annual weed that germinates from seeds each year. It dies each winter but before it does it will leave behind hundreds of seeds for next year.
When crabgrass gets to the point where it is seeding itself, it can be very hard to stop without an intervention. It will just keep spreading and spreading.
Related: Crabgrass identification

Conditions crabgrass thrives in

Crabgrass seeds will start to germinate when soil temperatures reach 55 degrees and remain at that temperature for seven to 10 consecutive days.
In northern Illinois, this means that Crabgrass will usually germinate sometime from late April to early May. This can vary based on the weather conditions such as a long winter, early spring, drought, rainfall, etc.
The best time to fight crabgrass is before it emerges. This way you can prevent it from growing, crowding out grass and spreading seeds.
Related: Q and A on crabgrass prevention and treatment

When to apply crabgrass preventer

crabrass emerging from lawnPre-emergent herbicides are the best way to control your crabgrass.
When you apply a crabgrass pre-emergent weed killer before it germinates from seeds, you should be able to prevent all or most of it from ever taking root in your lawn.
Apply crabgrass preventers approximately two weeks before germination.
In the Chicago area, that means that you should apply your pre-emergent week killer in approximately the third week of April.
Green T applies pre-emergent weed killer in our Round Two Lawn Application.
If applied at the right time in the spring you can prevent crabgrass from sprouting throughout the entire growing season. An application of a pre-emergent herbicide will last from 6 to 12 weeks, depending on the herbicide you’ve chosen.

How to apply crabgrass preventer

Apply your pre-emergent crabgrass preventer across your lawn as uniformly as possible. For easiest and even application, you can use a walk-behind or tow-behind spreader. You pour your bag of crabgrass preventer into the hopper of the spreader and use it to spread the pre-emergent across your lawn.
Because there are different types of preventers available, always read and follow the instructions on the packaging.
You will also need to water the area you have applied the herbicide. Depending on the product you will need to water within one to three days of application.
Watering helps break down the pellets and work its way into the soil. The chemicals need to make it down to the seeds that have worked their way into the soil over the winter in order to prevent germination.
Related: How to get rid of crabgrass in your lawn

Other ways to fight crabgrass

A healthy lawn is a great way to fight crabgrass and other weeds. A thick turfgrass will help crowd out weeds and not allow enough sun in for seeds to germinate.
red lawn mover - spring maintenanceProper mowing also helps keep annual crabgrass at bay. Mow your grass to no lower than a height of two to three inches. By mowing to this height you prevent seed germination by keeping the soil shaded. Crabgrass will be more aggressive on lawns mowed to less than two inches.
After the summer months are over, you should overseed your lawn and fill in any patches in your grass that formed during the summer. If you have bare patches in your lawn, you leave an opening for weeds to make their move into that space.
Related: Lawn mowing tips
We hope this article helps you keep your lawn crabgrass free!

Green T Lawn CareWould you like a professional to do the weed control work for you?

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