This is one time of the year that the perennial grassy weed, nimblewill stands out clearly in lawns.

Nimblewill is a warm season perennial grass that remains dormant until temperatures are more favorable. Our cool season varieties such as Kentucky bluegrass, turf-type tall fescues and perennial ryegrass are greening up nicely now; nimblewill is still brownish-gray in color.

Don’t confuse this with another warm season perennial grass called zoysiagrass which tends to have a yellowish, tan, straw-colored appearance at this time.

Some have planted zoysiagrass intentionally. It is a pretty tough and drought tolerant and some catalogues and garden magazines sell it for Midwest lawns. The disadvantage to zoysiagrass is that it’s dormant from mid-autumn to mid-spring, a lot longer than the other cool-season grasses. In addition, it produces a lot of thatch, which means that periodic dethatching is required.

Nimblewill is considered a perennial grassy weed in the Midwest because it’s very noticeable and out of place in our typical lawns. It grows in sun or shade and spreads where turf areas have thinned or in older lawns.

It spreads by seeds and by stems that touch the ground, forming dense patches. It resembles bermudagrass but is generally smaller and is more wiry in appearance. Once it gets a foothold in a thin turf area, it can spread quickly.

Prevention is the best cure for nimblewill. Maintaining a thick lawn makes it harder for nimblewill to get started. Believe, me, if you do not like its appearance in your lawn, you want to get rid of it as soon as you see it because it takes over!

Because it’s a perennial weed, the only thing that eliminates it is a nonselective herbicide or hand-digging it completely out of the lawn. A nonselective herbicide is necessary because there are no products that will kill just the nimblewill and not the desirable grass. Therefore, products containing glyphosate kills the nimblewill and any other grasses contacted.

Don’t spray the herbicide, however, until the patches are nice and green, otherwise it won’t be absorbed. In addition, spray about 12 inches out from the edge of the visible patch to kill any stems that are just beginning to root.

In some cases, this might mean that you are going to have a lot of brown spots in your lawn. You may consider total renovation if the lawn is primarily nimblewill. If you decide to hand-dig the patches, again, go out at least 12 inches. With either option, you can re-seed (10 days to two weeks after herbicide) and then concentrate on keeping the lawn thick through fertilization.