Use these simple methods to prevent and kill crabgrass, and avoid the big mistake that most people make in their lawn care program.
Come mid summer you are probably starting to see some of the negative effects the heat can have on your landscape. Your lawn is probably the part of the landscape that has you most frustrated.
As summer heat creeps in the more desirable grass types struggle, while weeds such as crabgrass thrive. Crabgrass can quickly take over your lawn and if you wish to have a crabgrass free lawn then crabgrass prevention, and removal should be a part of your lawn care program.
Why Is Crabgrass Bad?
Here’s the deal… some people have no problem having a yard full of crabgrass as well as other lawn weeds. In fact, the world is changing and there’s definitely a small movement forming where people are supporting natural lawns, or bee lawns.
But if you’re old school like me, you take pride in having a green, manicured lawn. This makes controlling crabgrass a big priority.
Crabgrass is an unattractive annual weed that enters your lawn (usually through bare spots). It dies in the fall when the cool weather sets in but not before spreading tons of seeds all over your lawn. These seeds will likely germinate the following spring and summer.
Prevent Crabgrass With Pre-Emergent Chemicals
Of all the lawn care products out there, pre-emergent chemicals are probably the most misunderstood and misused.
Most people rush to the stores the second the weather starts to get nice in early spring, and they load up on a step 1 product that most fertilizer companies push.
The step 1 for most of these companies contains a crabgrass pre-emergent and a fertilizer all in one. On the label you can find a very broad time frame of when you are supposed to apply.
There’s nothing wrong with applying a step 1 product to your lawn. But for it to be fully effective you have to have an understanding of soil temps, and you also have to apply more then once per season.
If you’re looking for a simple pre-emergent strategy then apply the step 1 twice. Your first application should be when your soil temps are approaching 55 degrees, and your second application should be about 5-6 weeks later as soil temps approach 70. This is a fine strategy if you want to keep things simple.
If you’re looking for a more effective pre-emergent for crabgrass as well as other broadleaf weeds then consider using Dimension or Prodiamine:
1. Dimension: Dimension (active ingredient Dithiopry) is a next level pre-emergent that is used by professionals. Dimension can be found in a couple of different products but my favorite and most accessible for homeowners is Lescos 19-0-7 Crabgrass Preventer.
Apply this product for your first two applications using the same soil temperature rules (approaching 55 and 70).
I actually recommend applying this product for a third time heading into fall when soil temps are decreasing. This will prevent Poa Annua seeds from germinating. Check out: Lawn Care Schedule Using 3 Products
Another great crabgrass pre-emergent is Prodiamine. Prodiamine is the name of the active ingredient so it can be found in several different products. It’s most commonly found in a product called Barricade. Barricade is a little harder to find in some regions but it can be found online. Also, if you are in New York, or other states where Dimension is restricted, then Prodiamine products will be your best option.
Soil Temps Are Crucial
Crabgrass starts to germinate when your soil temperature hits 55 degrees. The best thing you can do is find out when your soil temperatures usually hits 55 degrees and apply your crabgrass pre-emergent 14 days before that date.
You’re probably wondering how you’re supposed to know when your soil temperature is 55 degrees. Luckily, there is a great site called Green Cast Online.
All you have to do is go to the site and enter your zip code. Then click around using different dates from the previous year to see when the soil temps hit 55 degrees. You want to apply your step 1 14 days before this.
About 5-6 weeks later you want to apply the step 1 again as soil temps approach 70.
Once soil temps go above 80 degrees crabgrass germination comes to a halt. Adding a pre-emergent at this time won’t be very effective.
Spot Treat to Kill Crabgrass
While prevention is definitely the best method for managing crabgrass, it is likely you will still have some clumps of crabgrass that find a way into your turf. It is usually in the most vulnerable locations within your lawn.
The best way to kill crabgrass that is already established is to spot treat using a liquid, lawn safe herbicide such as Ortho Weed B Gone Plus Crabgrass Control. A product like this is easy to apply and best of all they will kill crabgrass without killing your lawn surrounding the crabgrass.
I recommend going out and walking your lawn once a week to spot treat new clumps of crabgrass that pop up.
If you have a more serious problem, meaning crabgrass is more mature or widespread, then I recommend using a product called Tenacity. Tenacity is a more professional product that works a little differently. It blocks photosynthesis from occurring in lawn weeds.
It is a selective herbicide so it will kill crabgrass and other lawn weeds without killing your lawn. If you have crabgrass everywhere then you can blanket spray your entire lawn with Tenacity.
When spot treating or blanket spraying, make sure conditions are dry so the herbicide sticks to the grass blades. Also, make sure you don’t apply before rain, or right before mowing. You want the herbicide to have time to do its job.
With enough persistence, you will eventually win the battle as the crabgrass dies off and your lawn fills in from routine fertilizer treatments.
If you have a more serious problem then you will probably be left with a lot of bare spots once crabgrass dies off. The trick here is to wait until early fall to fix those bare spots. Earl fall is a great time to top dress your lawn.
Manually Remove Crabgrass
If you just have some random crabgrass weeds that pop up here or there then consider manual removal. Sometimes I don’t have the patience to wait for chemicals to kick in. I prefer to get rid of it the moment I see it. The trick here is to manually remove crabgrass before it gets too big.
If it’s just a small weed simply pull it out by hand or use a really helpful weed pulling tool . If there is a more substantial patch then you have to dig it out using a shovel and that will create a bare spot in your lawn.
Removing smaller crabgrass weeds is definitely easier and better for your lawn!
Maintain a Healthy Lawn
It’s true. Nothing is better for combating lawn weeds then maintaining a healthy, full lawn. Sticking to a good lawn care program will allow your lawn to out compete crabgrass.
An established lawn with no bare spots makes it a lot harder for weeds to gain traction. If you have bare spots in your lawn then consider repairing them.
The Biggest Mistake Everyone Makes
Overall, the biggest mistake I see most homeowners make is applying crabgrass pre-emergent only once in early spring. Applying 2 applications 5-6 weeks apart is crucial!
Applying pre-emergent twice allows you to not have to worry about your timing so much. It can be hard to predict when crabgrass will germinate so applying 2 applications of pre-emergent takes away a lot of the guess work.
It also ensures that there is plenty of pre-emergent in your lawn over a longer period. This is important since there is a long period in spring/summer where crabgrass has the ability to germinate.
If you think crabgrass has taken over your lawn and the only way to fix it is to rip everything out and start over, you need to check out: Top Dressing Lawn: Benefits and Advice.
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