How to Kill Nutgrass Before It Takes Over Your Yard

You can kill nutgrass in your lawn or garden through the use of chemicals, but there are several other ways to control it if you prefer to stay organic.

Also called nutsedge, it isn’t, in fact, a type of grass at all; this herbaceous perennial belongs to the sedge family. The distinction is important, because herbicides used on true grasses will not be effective in killing nutgrass. This weed is commonly found in shrub beds, vegetable gardens, and flower borders, as well as in lawns.

Learn how to identify nutgrass, why it is bad for your lawn, how to kill it, and what preventive measures you can adopt to control nutgrass.

What Is Nutgrass?

There are two different types of nutgrass: yellow nutgrass and purple nutgrass. Both are named for the color of their seedheads. They are perennials and spread via root-like rhizomes and other underground plant parts called tubers (or nutlets). It is from these rhizomes and tubers that the new shoots of nutsedge emerge next spring. Nutgrass can also reseed.

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How to Identify Nutgrass

The best way to identify nutgrass (and thereby distinguish it from a true grass) is to look at the stem. Whereas a grass stem is round, the stem of nutgrass is triangular. The leaves of nutgrass are more rigid than grass leaves. The seedheads are also distinct from grass seedheads. Grass plants also do not have tubers.

Why Nutgrass Is Bad for Your Lawn

Nutgrass is weedy-looking, so it does not blend in well with a lawn. If you like that well-manicured look in a lawn, having nutgrass in it will be unacceptable.

But the problem goes beyond looks. Nutgrass will compete with your lawn grass. It grows in dense patches once established and is a faster grower than most lawn grasses. It grows so fast that it may develop seedheads (and drop seeds that will sprout and make new plants) before you even become aware of its presence. So in the competition between nutgrass and lawn grass, nutgrass will win if allowed to, crowding out the grass in your lawn.

The Best Method to Kill Nutgrass in Your Lawn

If you prefer to stay organic, it is possible to kill nutgrass in your lawn. But this weed is very persistent, and it will take several years to eradicate a well-established patch of nutgrass sticking to organic methods. This is why most people consider spraying with an herbicide the best method to kill nutgrass.

Applying an herbicide on the lawn is necessarily different from applying it in other areas, like a flower border. In a flower border, you have more options: you can use non-selective herbicides such as vinegar or glyphosate (as long as you use them carefully). On the lawn, you do not have these options, as these would also kill your grass.

Here is how to kill nutgrass in your lawn by spraying it with a chemical herbicide:

1. Find the right herbicide. You want a selective herbicide that will kill your type of nutgrass (yellow or purple) while leaving your type of grass unharmed. Halosulfuron-methyl is an example of an active ingredient contained within some commercial herbicides suitable for safely killing nutgrass on many types of grass, but check the product label for the right match for you.
2. Spray at the right time. The best time to spray is when the nutgrass is actively growing. At this time, the nutgrass will be busy sending nutrients down to its tubers to be stored. The herbicide will hitch a ride with the nutrients down to the tubers. This is important, because it is especially the tubers that you need to kill.
3. Aid the herbicide by watering. Water your lawn the day prior to applying the selective herbicide. The nutgrass takes up the herbicide better if the soil is moist.
4. Avoid mowing. Do not mow the lawn for a while before applying the herbicide. This lets the nutgrass get big enough so that you will have a greater surface area to spray (promoting superior absorption). Nor should you mow for a few days after applying the herbicide: You want to allow sufficient time for the nutgrass to absorb the herbicide.

4 Tips to Prevent Nutgrass From Coming Back

There are a few preventive measures you can take to keep nutgrass from coming back (or keep it from invading your lawn in the first place). Most of these measures entail helping your lawn grass in every way possible by giving it the conditions it needs while depriving nutgrass of the conditions it prefers:

• The tubers of nutgrass are sometimes spread by accident. For example, you may have fill dirt brought onto your property that has nutgrass tubers in it. Or you may inadvertently transport the tubers from one part of your land to another when you transplant a shrub or reuse landscape equipment (such as a rototiller) without cleaning it first.
• Mow your lawn at the proper height.
• Fertilize your lawn according to schedule.
• Since nutgrass thrives in wet soil, make sure you do not over-water the lawn and have proper drainage.