Crabgrass in the Fall – Having a Completely Crabgrass-free Lawn is a Tough Chore!

Crabgrass growing next to a sidewalk

Crabgrass growing next to a sidewalk  >>> Image Source: Purdue Turf Tips, Weed Management Next to Sidewalks and Driveways (July 14, 2014) – CLICK ON THE IMAGE TO READ MORE

As most of you are WELL aware of, crabgrass is a common summer annual weed in our Michiana lawns.  In July, crabgrass plants were busy flowering and spreading their seeds, but each year it will die out naturally after the first frost.

But what can you do about crabgrass in the months between July and October/November when we usually see our first frost?

Unfortunately, the best time to control late summer / early fall crabgrass is to go back in time and deal with it in THE SPRING with a PRE-EMERGENT herbicide (like our 13-0-5 Fertilizer + Crabgrass preventer), along with mowing right, watering right, and fertilizing right.

Crabgrass is tough to kill and reproduces very effectively.  To expect a 100% crabgrass-free lawn is probably not very realistic – Mother Nature has the upper hand. The most effective approach to controlling this weed is to nurture and maintain a dense, healthy lawn to out-compete crabgrass (and other weeds by default), and prevent it from establishing in the first place.

We’ve been getting quite a few calls and visits from customers whose lawns are mostly free of this weed EXCEPT along areas like the edges along sidewalks, driveways, and roads.  These sections have two major issues going against them:

(1) SALT from winter that is still hanging around in the soil; and

(2) COMPACTION from things like foot traffic, auto/mower tires, and piled snow.

Crabgrass – among other weeds – is very tolerant of growing where there is salt and compaction.   Turf grasses are sensitive to both salt and compaction, and tend to NOT grow well in these spots.  Kentucky bluegrass is especially sensitive to salt damage, while perennial ryegrass, fine fescues, and tall fescue are more tolerant, but not totally resistant.

Another common trouble-spot is along the seams where sod was laid but the edges of the rolls were probably not placed close enough together.  The turf growing in these seams is thin and weak, allowing weeds to out-compete your grass.

Again, the crabgrass you see now in late-August WILL die off with our first frost.  But what about using a POST-emergent herbicide?  There are effective products to use, but TIMING is everything and ALWAYS READ THE LABEL.  Common to these post-emergent crabgrass herbicides is that you need to apply them when the plant is YOUNG … and, well, once we get past mid-July the crabgrass plants are usually
too large to control effectively. Another challenge to treating crabgrass that has already shown up is that these post-emergents work best at temperatures below 85ºF on clear days with low humidity.  That’s pretty hard to do in the dog-days of summer!

So what do I do this time of year in my own yard? I pulled a few out of my front yard the other day. I have more in the backyard and I plan on leaving them. I am not going to try to attempt to eradicate them with herbicides at this time. They are very big and tougher to kill. I am going to tolerate them because they will die with the first frost. Every year I tell many customers that you can apply Crabgrass preventer 2 times in a year.   If crabgrass was bad this year, I would look to doing better prevention next year.

On the other hand, if you’re up for the challenge, we do carry some post-emergent herbicides that we’d be happy to educate you about.

For more in-depth, science-based information, check out Purdue Extension’s publication, “Control of Crabgrass in Home Lawns” by CLICKING HERE.

As always, give our team a call if you have any questions – 574-232-6811.

Jeremy and the Red Hen Turf Farm Team


6 thoughts on “Crabgrass in the Fall – Having a Completely Crabgrass-free Lawn is a Tough Chore!

  1. Now that summereis over and we are here in fall or early winter my lawn was full of crab grass so much it’s not possible to go out an sputt each one up. but they look brown and horrible. Tell me is that anyway I can or need to get rid of them before I spread new grass see early Spring, Do they go away on their own or do I need to find a way of getting each root out of the ground.

    • Good question! Let’s start with the basics. Are you “local” – in the Michiana / Indiana / Michigan area? We’d be happy to help from there, but believe it or not, where you’re located makes a difference in approach. Generally, using most types of herbicide (crabgrass or broadleaf) will reduce your effectiveness with seeding – timing is everything and baby grass plants cannot tolerate herbicides very well. Feel free to call us to talk more about your particular situation and your planned projects for spring 2019 – RED HEN TURF FARM (New Carlisle, Indiana) 574-232-6811

  2. I live in Washington state and crabgrass has took over my lawn. I plan on over seeding in fall. What will happen to the areas that the crabgrass has taken over?

  3. Crabgrass took over about half of my front lawn this summer. With the cooler temperatures the last few weeks (I live in Grand Rapids, MI), the crabgrass has slowed down, weakened, and browned. The sheer amount of it is troubling, and it’s unrealistic to pluck it all out by the roots. I know crabgrass will die completely with the frost. That’s great. My question, though, is whether I can just leave it and then, early in the spring, either overseed or use a patch/repair product, or, do I need to somehow physically remove the crabgrass at some point in order to seed effectively (i.e. does the crabgrass actually disappear after it dies)? Either way, I plan to also use a fertilizer and crabgrass preventer in the spring. Any suggestions and/or points of clarification? Thank you!

    • Hi, thanks for your question.

      If you do a seeding in the spring you will not be able to use a crabgrass preventer at the same time. Look up the chemical Tenacity and order some of that (here are some blog links we wrote that includes information on Tenacity for weed control when you ALSO want to do a seeding:

      Tenacity will help you with your seeding by keeping the spring weeds at bay. I would then read up on seeding in the spring from Michigan State University since you are 2 hours north of our location. Here’s a shortcut for some Google Results that should help with that –

      If you’d speak in more depth, please call our landline 574-232-6811 – Thanks from Jeremy at Red Hen Turf Farm

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