I’ve been getting lots of questions lately about nutgrass and nutsedge, also known as kyllinga, purple nutsedge and yellow nutsedge.
Most of my advice on these weeds is in my book “New Decade Gardening,” but I think it’s worth tweaking some of my standard tips here.
For the first time in all my years of doing on-site consulting, I recently came across a yard that had all three versions of this detestable weed. (ABOVE) Normally, it’s just one or sometimes two. But one thing is clearly clear: Nutgrass or whatever you want to call it is a SEDGE. It’s not a grass weed, and it’s not a broadleaf weed. It is in its own category!
Nutsedges or nutgrasses are common turfgrass weeds that favor warm climates and poorly drained or over-irrigated areas. Golf courses often provide ideal environments for some of the more common species, including purple nutsedge, yellow nutsedge, globe sedge, rice flat sedge, annual sedge and kyllinga. Kyllinga, especially, is becoming more prevalent on courses.
Most of us in Southeast Texas are fairly familiar with nutsedge, the thin-bladed weed I think looks like monkey grass on Quaaludes. The little nutgrass rhizomes (nuts) can be found as deep as 18 inches in the ground and can sit dormant for nine years. You can pull it out, but you’ll be leaving the nuts in the ground. That's why pulling is bad. Herbicide controls work really well, but they can take up to two weeks to produce results. The best are sulfentrazone-based.
Forty-five species exist in the world, but only five are currently found in the continental U.S. Most are rather difficult to detect in turfgrass because their growth closely resembles that of turf.
There are two forms that are often hard to identify. One is the uber-thin sedge that almost always sets up shop in the wettest of areas, and I often get questions about a sedge that has burrs on top.
Kyllinga (pronounced kul-LING-uh) sounds a little like kill-ling-uh, and that's exactly what you should do to it. Kyllinga leaves are glossier than turfgrass and are detected easier in the morning as dew falls off their leaves but remains on the turf. Kyllinga also has a distinctive "minty sweet" scent when the leaves are mowed or crushed.
Another type - green kyllinga - also produces seed throughout the growing season and is commonly misidentified as burrgrass. It is not. It’s a sedge, and that means typical burrgrass herbicides won’t affect it. Its seed heads are about the size of a garden pea and have a light green color. The seeds germinate in spring and throughout the summer. But when you have, it you want to kill it, right? That’s where post-emergent controls specifically for nutgrass and kyllinga come in to play. There are three readily available.
The Most Popular Brands of Nutgrass Control
- Sedgehammer by Gowan
- Nutgrass ‘Nihilator by Monterey
- Sedge Ender by Bonide
- Image by Lily Miller
I recommend Sedgehammer most often because it can be used at any time of the year. Sedge Ender is a readily available sulfentrazone-based control. Nutgrass ‘Nihilator works, but it’s not sulfentrazone-based and can be hard to find in this area. And then there’s Image. It was once the “go to” product for nutgrass, but Image also damaged many St. Augustine lawns. Turns out that Image is not safe to use on St Augustine in warmer months when temperatures are 90 and above. Likewise, when temperatures dip to 50 and below, Image is also more damaging to the lawn than it is to the weed. Bottom line is Image has a very narrow window for use: March, April and May.
The key to success with any nutgrass control is to use a surfactant with it. Some of the herbicides above advise against adding any surfactant, so do a test run in those cases. Spray a little on a test patch and see if it actually adheres to the slick leaf surface. If it runs straight off, add a surfactant.
There is also an organic treatment for nutgrass, but its effectiveness is very hit-and-miss. I’ve heard as many “it didn’t work” stories as I have heard tales of success with using molasses. Usually you mix ½ cup of agricultural molasses with one gallon of water. Here too, I would add a bit of surfactant to the mix. One issue with molasses is that you may still see nutgrass blades, but it really does work on the “nut” part of the weed.
Pre-emergent herbicides such as Barricade or Dimension also have hit-and-miss success in controlling nutgrasses and nutsedges. So, early detection and early treatment is the best way to control this annoying weed - don’t ignore any of the three examples at the top of the page when you first see them.