How to Kill Nutgrass in Flower Beds

Purple and yellow sedge are the two most common.

Nutgrass, better known as nutsedge, is a tuberous weed that looks like grass and invades lawns, flower and vegetable beds. While lawn grass stems are hollow, sedges have solid stems as well as blade-looking leaves that grow in groups of three at the plant's base. All sedges are tough weeds and difficult to control, but not impossible. The best strategy is to combine diligent cultural practices with chemical treatment to maintain your flowerbed free of this weed.

Things You'll Need

• Gloves
• Hoe
• Tall flowering shrubs
• Polypropylene polymer landscape fabric
• Bark or gravel mulch
• Glyphosate herbicide
• 1 tsp. dish washing soap (optional)
• ½ c. ammonium sulfate (optional)

Instructions

1. Pull nutgrass seedlings as they pop through the ground and before they develop six leaves. At their growth rate, you'll be removing nutsedge about every two weeks. This step keeps weed from developing new tubers and depletes the existing one of energy, which it keeps using to replace the seedlings you pulled. Eventually, the tuber runs out of steam.

2. Plant tall flowering shrubs in your flowerbed to create shade. Since nutgrass is a sun-loving weed, the University of California believes this would eventually decrease the number of thriving nutgrass tubers in your flowerbed.

3. Install landscape fabric in your flowerbed, covering as much ground as possible around the base of your flowers. Apply a layer of bark or gravel over the fabric to hold it down and make the bed attractive. Use landscape fabric made of polypropylene polymers. Nutsedge's tough blades are able to cut through black polyethylene plastic mulch.

4. Apply one of the several glyphosate herbicides available for sale. This chemical is also likely to kill flowers it comes in contact with. Therefore, wet only the nutgrass. Following the manufacturer's instructions, spray the weed when it has six leaves. The best seasons for treatment with glyphosate are mid to late spring, early summer and one month before the first frost in the fall.

Tips & Warnings

• Before applying glyphosate, mix it with 1 teaspoon of dish washing soap and ½ cup of ammonium sulfate per gallon of herbicide. Texas Cooperative Extension says the soap helps the chemical to stick to the nutsedge and the ammonium sulfate increases the weed killer's effectiveness.

References

• University of California IPM Online: How to Manage Pests
• University of California IPM Online: How to Manage Pests
• Texas Cooperative Extension: Going Nuts over Nutsedge