I had two raised beds built for a vegetable garden. So far, all the veggies look healthy but so does the nutgrass that won't stop growing along with the veggies.
Is there anything I can do other than removing all the soil and starting over?
I know nutgrass is impossible to get rid of, but because of the vacant lot next door, I give up. I was so much looking forward to some wonderful tomatoes, eggplant and peppers!
Lois Hoeffel, Fair Oaks
According to UC Master Gardener Geoffrey Wood, your nutsedge commonly called "nutgrass" is most likely yellow nutsedge (Cyperus esculentus), as purple nutsedge (C. rotundus) is less common in Sacramento.
Nutsedges are especially problematic with annual or perennial crops that receive summer irrigation. They thrive in waterlogged soil. However, drying the soil will not eliminate yellow nutsedge tubers.
Both nutsedges reproduce via underground tubers, which look like little nuts (hence the nickname). Controlling the nutsedge means controlling or eliminating the tubers.
Getting rid of nutsedge takes effort and persistence. The primary means of controlling nutsedge tubers is by repeatedly removing them. When young plants have five or six leaves, remove the whole plant roots, tubers and all.
You'll have to do this every two or three weeks in summer. This will starve the tubers, but be patient each tuber can re-sprout three to 12 times before it's depleted.
Tubers can be found as deep as 14 inches in the soil, but most will be in the top 6 to 8 inches along with most of the roots.
Alternatively, one can remove the tubers with a hand hoe. If using a hoe, dig down at least eight to 14 inches to be sure to remove the whole plant.
One can also cultivate the soil with tools like a tiller, but it must be repeated every time the plants get to that five- to six-leaf stage, or else cultivation will just spread the nutsedge.
Nutsedge growth can also be limited by shading the plants or solarizing the soil, which will weaken shoots and decrease new tuber formation, but may not eliminate mature tubers.
Nonwoven landscape fabric covered with mulch can help suppress and weaken nutsedge, but it will not eliminate the mature tubers. Cut holes in the fabric for your vegetables.
Additional information on eliminating nutsedge is available online at www.ipm.ucdavis.edu.
Few chemicals are effective at controlling nutsedge. At this time, University of California's integrated pest management program is not aware of any herbicides that would be appropriate for managing nutsedge within a mixed vegetable garden.
Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties.
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