Controlling Nutgrass in Lawns

Q. I have a common lawn with my neighbor and it has an infestation of nutgrass that is now spreading into my lawn. How do I stop it? I've read sugar is a good alternative to herbicides but I would like your help to get this under control.

Nutgrass or nutsedge looks like a grass but it grows faster and it can have darker green leaves if it is purple nutgrass.

A. I have never heard about sugar used to control weeds. That is a new one on me.

            Nutgrass, sometimes called nutsedge, is a tough weed to control. Because it’s a sedge, the leaves look very similar to lawn grasses like fescue. Many people don't know it's in a lawn because it looks similar to the grass. It does grow faster than lawn grass and that can be a giveaway. It's also more upright in its growth so that can also give it away. And, of course, when it sets flowers and seed that can give it away.

If you look closely you can see the nut , the namesake for nutgrass. This is its survival mechanism when things go wrong.

            Nutgrass is called that because of the “nut” or tuber that grows below ground. It’s usually brought into home landscapes as a weed when buying nursery plants. Most people think it’s a grass and pull it but the nut in the soil is left behind. The plant and its soil are planted. From there it spreads.

            When it’s pulled like a weed from the soil, the leaves separate from the underground nut easily. The underground nut regrows new leaves. If the leaves are pulled over and over, as soon as you see them, the nut eventually gives up, exhausted, and dies. That is a common “organic” strategy for controlling nutgrass without chemicals.

Very sturdy nutgrass plant probably because it was growing in a vegetable garden.

            It’s also a common strategy when using chemicals. Weed killers burn the top of the plant down, over and over, until the nut just gives up.

            A weed killer that can be sprayed on the grass and only damages the nutgrass is available. It is called “Sledgehammer”. It’s only available for purchase online. In prior years it was only used by professionals. That formulation was called “Manage”.

            A similar strategy is used when spraying Sledgehammer. But sledgehammer actually kills a fair number of the nuts as well. But not all of them. So, it must be sprayed again when the leaves appear.

Sledgehammer available from Walmart

            When to make the second and third applications is very critical. The spray must be applied when the nut has “invested” its energy into the growth of new leaves. Wait too long and the leaves will rebuild the nut. As soon as they appear, no more than four leaves, Sledgehammer is sprayed again. Eventually, after repeat sprays at the right time, you have won the battle.