Crab Grass Taking Over

Hello, all. I’ve had my Rachio for about 3-4 months and for the most part I like it. I have had many neighbors ask me how my lawn is looking so green.

But I am starting to see a bunch of crab grass taking over my kentucky bluegrass / tall fescue blend. I know that one way to help eliminate it for good is to water deeper (longer less often). But here in Inland Empire of Southern Cali (apparently loamy sand) my flex schedule is watering many sections about 5 times a week.

So my question is in general what is the best way to attack this problem?

I think my roots are only about 4 inches deep or so. But I have my sections set to be 6 inches in hopes of promoting deeper growth. Is this a good approach?

I am at a loss here, and I apologize for the rambling. Any suggestions would be greatly appreciated. Thanks!

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You control crabgrass by applying a preemergent herbicide in the spring. If the weed seeds are there they will germinate throughout the warm months. Deep watering, light watering crabgrass grows anywhere. Inland Empire? What is this? I have never heard of an inland empire.

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The Inland Empire of Southern California is a nickname for the San Bernardino/Riverside/Redlands area. Pretty dry and hot, but not as bad as the higher deserts (Barstow/Victorville) or Palm Springs.

How would I get rid of it then if it has already taken hold? Dig it out and replace it with seed or sod in the fall?

This is some good info from the California Cooperative Extension Service:

I am hesitant to make post-emergent herbicide recommendations because I do not know what is labeled in California.Plus, California has unusual growing conditions. Raise your mowing height to 3 inches. That will help shade out weeds. There are also natural methods, but I am not sure how well they work. Here in Oklahoma, we reseed in the fall and winter kills out weeds like crabgrass. Then apply preemergent twice in the spring.
Another option is to hire a lawn weed and fertilizer company. Good luck. If you buy a herbicide product ALWAYS read the label.

Thanks for the info on the Inland Empire.

I’m a fan of this product.

Not promoting the vendor, just the product, is legal in cali.

Here is the registered ai For cali



You will find plenty of active products with these chemicals.

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Great. But before applying always read the product label. I know with some products they will tell you not to apply when temperatures are high. Don’t assume. I can speak from experience.

Xlr8 get it on Amazon. Amazing stuff.

I live in North Carolina so you may need to check with your local extension office for specifics for your area. Here the best way to control crab grass are the following steps.

  1. Fertilize at the correct times. For us Labor Day, Thanksgiving and Valentines day for fescue. If you fertilize into the summer you are just aiding the weeds.
  2. In early spring put down a pre-emergent.
  3. Mow to a height of 3.5-4 inches. There is an NC State study on mowing height and crab grass validating the importance of not mowing short.
  4. There are a number of post emergent controls. If our state has an agricultural manual check it otherwise you can Google and look at the one for North Carolina.

Watering may be a factor but I suspect its not the prime consideration.

Good luck.

Joe Spears
NC County Extension Master Gardener

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