Mario Bautista
People tell me they have been working on their lawn to make it look perfect. Everything looks great except for that ugly crabgrass. No matter what you do it comes back every year. It appears in spring and takes over in summer.
The ultimate goal is to have a weed-free lawn. But you guessed it − that one plant gets in the way of a perfect lawn – crabgrass. This invasive plant spreads by seed. It has wide leaves that form a tight, crab-like circle. You will see crabgrass pop up during spring and rapidly takeover during summer as temperatures ram up. However, if treated properly it can be eliminated before it takes over your lawn and prevents it from coming back.
What is crabgrass? Crabgrass is an invasive warm-season grass that can spread in favorable conditions. There are 12 varieties of warm weather annual grass. The most well-known variety is Digitaria sanguinalis.
Crabgrass will return annually
Crabgrass seeds germinate as temperatures warm up around the spring and summer. From there it flourishes until it dies and leaves big, circular dead spots in your lawn. It does come back the next spring year after year after year if you don’t destroy the seeds.
OK, so how do you get rid of crabgrass? The best time to kill crabgrass is in the spring with a pre-emergent herbicide, which prevents weed seeds from taking root. Using a corn gluten-based product, either liquid or solid, spray the crabgrass with the pre-emergent herbicide according to the instructions on the product’s label.
Follow the instructions carefully. Pre-emergent herbicides kill the weed seeds before they have a chance to appear above the surface. If correctly timed a pre-emergent application will significantly reduce the amount of time you spend later in the season dealing with crabgrass. The crabgrass already growing will not be affected.
So if you have already missed this window you can kill crabgrass right after it emerges and is still in the leaf phase. Use a post-emergent herbicide to control weeds after they have emerged from the soil. Spray the crabgrass with the post-emergent herbicide according to the instructions on the product’s label.
Dedicated people can remove crabgrass by hand
You also can remove crabgrass by hand once it forms. This method takes a lot of time, but is very effective. Use your hands or a garden weeder, pull the crabgrass out of the ground by the root making sure all is removed.
The best way of preventing crabgrass all together is by using proper lawn care, which prevents bare spots and keeps sunlight from the soil so the crabgrass seeds cannot sprout. Mow your lawn regularly. This will encourage grass to thicken up and grow horizontally. It is an effective control for broadleaf weeds, which need to grow quickly and spread their large leaf system to support it. When you mow, it interrupts that process by cutting the weeds off before they can fully develop.
The best defense against crabgrass is a thick dense turf
How about fertilizer? Well thick, dense turf is the best defense against crabgrass. Fertilizing regularly thickens up your lawn and will crowd out the crabgrass and other weeds. Just make sure you remove all phosphorus from your spring fertilizer applications because any added phosphorus will be absorbed by the crabgrass and will speed up its lifecycle.
Remember to water deeply and infrequently which will keep the roots driving deep in search of water. The average homeowner will water a few times a week for about 20 minutes each time, that’s the default setting on their irrigation clock. Watering too often and for short periods of time encourages a shallow root system. This also only waters the top layer of the soil, which benefits shallow rooted weeds like crabgrass.
So, what if you neglected your lawn for a period of time and the crabgrass is making a big appearance? Not to worry. Let the crabgrass die in the fall. It will leave an ugly brown mess and lots of bare spots. You will need to thicken up your turf by re-seeding. Late in August is the best time to seed cool season grasses so your lawn will be thick and dense next spring.
If you hire a lawn service company, they will handle all the problems and explain every step they do.
Susan La Fountaine is a Master Gardener with the Sandusky and Ottawa County Extension Offices.
