Helpful Tips About Trees, Lawns, and Pests

How to Get Rid of Crabgrass & Kill Lawn Weeds in Summer & Fall

Written by Joshua Malik | Aug 28, 2018 11:23:00 AM

Crabgrass and other weeds can wreak havoc on your lawn. These opportunistic weeds require very little nurturing to thrive and they can quickly take over an entire lawn in very little time.

If you forgot to treat your lawn in the spring and throughout summer or fall you realize that weeds have truly taken over, you might be wondering is it too late?

You’re thinking about getting rid of crabgrass in the summer or fall, but you don’t know if it’s even possible.

Dealing With Mature Weeds in Summer

First of all, you should know that you are not alone. Life gets busy and flies by. You may have had the intention of treating your lawn in the spring but it just never happened. Or maybe what you did just didn’t quite do the trick.

This is quite common and we get a lot of late-in-the-season calls from homeowners who are desperate to know what they can do. After all, a lawn overrun by weeds is unattractive—but so is one that is full of bare spots and once all those weeds die off as it gets colder, that’s what’s going to be left.

If you want to know the best steps for getting rid of crabgrass and killing lawn weeds in the summer and fall, then we’ve got you covered. Here’s what you should know.

How Do Crabgrass & Weeds Spread?

First, you should know that it doesn’t take much for crabgrass to spread.

Between mid-summer and early fall, a single crabgrass plant produces thousands of seeds—as much as 75,000 a piece—and these seeds get mowed off and dropped to the soil below. Those seeds lay dormant in the soil until the time for germination is just right.

With those kinds of numbers, it’s easy to see how (in just a little bit of time) your lawn could become completely overrun by crabgrass. 

Even if you only forgot to treat for crabgrass this past spring, there could be hundreds of thousands of crabgrass seeds that sprout and cause you a big mess come summer or fall.

While most broadleaf weeds are not quite as aggressive as crabgrass, and won’t crowd out healthy turf quite as successfully, their seeds can also be easily scattered.

Just walking through your grass can spread weed seeds around your yard. Some species even project their seeds 10-15 feet away when the time is right for their proliferation.

How Does Crabgrass & Weed Control Work?

It might help you to understand how crabgrass control works before further discussing seasonal control. A granular lawn care material is applied to the entire lawn in spring, dissolving to form a thin barrier near the surface of the soil.


This barrier intercepts the crabgrass seeds and stops them from growing, preventing the majority of crabgrass from ever growing in the first place. It’s about 80-90 percent effective in thick turf areas, providing it’s a year with typical rainfall.

Similarly, for broadleaf weed control, the idea is to stop the growth before it has the opportunity to rapidly spread. Most broadleaf weeds require post-emergent materials meaning they have to be present for the product to work.

Since weeds germinate throughout the year, it’s important to have multiple applications of control materials.

But what if you missed that opportunity to prevent crabgrass or spray weeds throughout the year? What if you’re wondering about killing lawn weeds in summer or fall? Let’s take a look at each of these seasons.

Killing Lawn Weeds in Summer

If it’s summertime when you realize that crabgrass and other weeds have taken a stronghold of your lawn—and you never applied pre-emergent products—then you should still attempt post-emergent treatment.

At Joshua Tree, we would use liquid post-emergent weed control products to try and suppress as many of those weeds as possible. It’s not going to be as effective as pre-emergent treatment would have been for crabgrass, but it will still help in the effort to get your crabgrass problem under control.

In the case of broadleaf weeds, some species are more easily controlled than others, so multiple applications may be needed until these weeds are taken care of.

Killing Lawn Weeds in the Fall

By the time late fall rolls around, it’s possible that it may not be worth treatment. That’s because crabgrass and some weeds will die off with a heavy frost.

Depending on how far off it is from the colder season, it may just be advisable to wait, and then get your lawn in better shape for spring. This may be decided on a case-by-case basis.

It’s also important to note, if you're getting rid of crabgrass in fall, it could interfere with aeration and overseeding, which should also take place in the fall.

If you treat the lawn with post-emergent weed control, it’s also going to kill your newly germinating lawn if you don’t wait a week or more.

The best option would be to apply weed control products in early fall, then wait a week or more to perform an aeration and overseeding. This will get rid of the majority of your weeds and allow the new grass plants enough time to germinate before winter comes.

Next spring you will be able to apply pre-emergent crabgrass control and treat broadleaf weeds as normal, to keep them from invading your newly-improved lawn.

A Full Program for Future Success

While we’ll do the best that we can to get crabgrass and other weeds under control late in the season, the best step that you can take going forward is to get on a full program that will prevent a weed takeover from happening in the future.

That not only means getting crabgrass preventer and pre-emergent broadleaf weed control down early in the spring to prevent them from germinating, but also thickening up your lawn to help crowd out undesired growth in the first place.

If you have lots of thin or bare patches where crabgrass died, then you’ll also want to consider aeration and overseeding to restore your lawn.

Stop beating yourself up for failing to be proactive. Even with reading this article, you’re already taking steps now that will set you up for future success. You already know just how fast time flies.

In hardly any time at all, you’ll have the healthy and thriving lawn that you’ve always desired. That means you can cast your worries, and your embarrassment, aside and start feeling proud of your beautiful lawn.

With the right care for your lawn, you’ll gain valuable peace of mind. If you’re interested in having your lawn inspected and its health assured, contact us for a free quote or give us a call at 833-JTE-TREE.