How to Kill Nutgrass in a Garden

A hoe may be all you need if you catch nutsedge early.

Nutgrass, also known as purple sedge and nutsedge, is an invasive plant that reproduces from seeds and tuberous roots. Tubers are thick sections of underground stems known as rhizomes. The nutgrass tubers become established at a depth of 8 to 14 inches and spread horizontally, propagating the weed. Within each tuber, there is energy sufficient to grow 10 feet in diameter worth of nutgrass. First, try eliminating the weed by natural means. Use chemicals as a last resort.

Things You'll Need

• Hoe
• White vinegar
• Corn gluten meal
• Hydrogen peroxide
• MSMA-based herbicide

Instructions

1. Hoe young nutgrass or pull it by hand before it unfurls its fifth leaf. That indicates the tuberous root has not multiplied yet, making it simpler to eliminate the weed. Be diligent about pulling the plants as soon as they appear to exhaust the single tuber sending out the shoots. The depleted root eventually dies.

2. Irrigate the garden through mid-summer, then withhold the water to kill the nutgrass tubers of heat and dehydration. Of course, this option may also destroy other plants growing in that patch of earth. If they are replaceable, it might be worth sacrificing them to get rid of the nutgrass.

3. Dig around the weed to find out how deep the tubers are buried.

4. Pour white vinegar sufficient to saturate the root zone. The acetic acid kills the roots.

5. Broadcast 20 pounds of corn gluten meal per 1,000 square feet in the plot where nutgrass usually germinates. Do so halfway through spring to catch the seeds before they sprout. Corn gluten meal is a natural pre-emergent weed killer that destroys seed embryos before they get a chance to develop. Water the soil after broadcasting the product to activate it. Repeat the treatment the following years until you completely eliminate the weed.

6. Drench the soil with hydrogen peroxide in the spots where nutgrass normally sprouts. The fluid adds oxygen to the ground. Nutgrass, a weed that thrives in anaerobic -- or oxygen-deprived -- environments dies in the oxygenated site.

7. Spray nutgrass with an herbicide containing the chemical MSMA as its active ingredient. The product comes as different brands. Read their labels to find out whether the formulas are safe for the type of grass and other plants growing around the weed. Follow the manufacturer’s instructions for rates of application and frequency. Multiple treatments may be necessary to eradicate nutgrass.

References

• University of California; Nutsedge; C.A. Wilen, et al.; March 2010
• USDA Agricultural Research Service; Vinegar: More Than Just a Salad Dressing?; Don Comis
• “Dirt Doctor Organic News #19”; Nutgrass (Nutsedge for the hort enthusiasts); Howard Garrett; 2010
• University of Minnesota Extension; Corn Gluten Meal: A Natural Pre-Emergence Herbicide; Jean Galligan, et al.; January 2002
• MSUCares.com: Weeds in Mississippi--How Can I Control Nutgrass?