There are many kinds of sedge or "nutsedge" (genus, Cyperus) plants, and some of them are considered invasive outside of their native ranges. This genus belongs to a family related to the grasses (Poa). While many are weeds, some of them are showy enough to be treated as if they were ornamental grasses, but these grass-like plants are not true grasses. It is easy enough to identify a sedge and distinguish it from a true grass: A sedge plant will have triangular stems in cross-section, whereas a true grass will have round stems. Even sedges that have ornamental value have inconspicuous flowers and are grown for their foliage, not their blooms.
Because this genus is so diverse, it is perilous to generalize about it. Consequently, we will use yellow nutsedge as an example, discussing this particular nutsedge in detail and mentioning others as the context warrants. Yellow nutsedge is considered invasive in the United States and listed as a noxious weed in some states. Its native range extends from the Mediterranean to India. There is a debate as to how it arrived in the United States, with some even suggesting that its plant parts capable of self-propagation originally floated across the ocean from Africa to arrive on American shores and establish themselves. Homeowners with lawns that suffer from wet patches will be especially eager to learn how to get rid of yellow nutsedge, since, once established, it is very difficult to remove from such areas.
Regardless of how it arrived in North America, yellow nutsedge is found across the United States and listed as invasive in Michigan, Colorado, Washington, Oregon, and California.
Yellow nutsedge is considered a problematic invasive because it spreads quickly and is so difficult to get rid of. Its great ability to spread is due to the fact that it can spread in several ways, both through above-ground plant parts and below-ground plant parts. Sedges typically grow where the ground is wet and where there is full sun.
|Common Names||Yellow nutsedge, yellow nut grass, water grass|
|Botanical Name||Cyperus esculentus var. esculentus|
|Mature Size||12 inches tall, with a spread of 6 inches|
|Soil||Prefers moist soil|
|Bloom Time||June to October|
|Hardiness Zones||4 to 10 (United States)|
|Native Area||Mediterranean east to India|
What Does Nutsedge Look Like?
The inconspicuous flowers of yellow nutsedge come in clusters, each 3/4 inch to 1 inch long and resembling bottle brushes, at the tops of the stems. The leaves of yellow nutsedge are alternate, basal, yellowish-green, have a waxy coating, and sometimes exceed the stems in length; its stems average about 12 inches in length but can be longer or shorter depending on growing conditions.
But there are many types of sedge, including:
- Purple nutsedge (Cyperus rotundus): Another weedy nutsedge, it is smaller than yellow nutsedge (only up to 6 inches tall at maturity). Its leaves are a darker green, and the plant bears reddish-purple seed heads. Less hardy than yellow nutsedge (only as far north as zone 7), it is a problem in lawns of the southern United States.
- Papyrus (Cyperus papyrus): Papyrus is the best-known of the sedges, famous for its ties with ancient Egypt. A tall, stately plant (5 to 8 feet), it is a perennial in zones 9 and 10. Northerners commonly grow it in patio pots or install it in water features for the summer.
- Japanese sedge (Carex morrowii): An ornamental like papyrus but smaller (12 to 18 inches), this type of sedge is valued for its variegated foliage and often used as an edging plant for zones 5 to 9.
- Chufa (Cyperus esculentus var. sativus): This type of sedge is grown as a food crop in zones 8 to 10. It has several common names in addition to Chufa, including tiger nut, earth almond, and rush nut. Confusingly, authors often use these common names interchangeably with the common names for Cyperus esculentus var. esculentus and vice versa.
How to Get Rid of Nutsedge
Where yellow nutsedge is invasive, it is very difficult to get rid of. For one thing, this perennial weed has multiple methods of self-propagation: seeds, rhizomes, stolons, and tubers. Secondly, these tubers can remain viable in a state of dormancy for several years. As is often the case with weed control, taking preventive steps is preferable to trying to get rid of a well-established patch of yellow nutsedge after the fact. Preventive steps include mowing high (3 1/2 inches), ensuring that your lawn has good drainage, and keeping yellow nutsedge from going to seed. Mowing high helps your lawn grass outcompete yellow nutsedge, crowding it out and depriving it of sunlight. Good drainage deprives yellow nutsedge of a growing condition it craves: wet soil. Keeping yellow nutsedge from going to seed (which can be achieved by hand-pulling on small patches) robs it of one of its means of self-propagation.
But preventive steps are not always sufficient. An organic way to get rid of a well-established patch of nutsedge is to dig it out, paying particular attention to removing as many of the underground plant parts (tubers, etc.) as possible. You will still inevitably leave some behind, so plan on having to dig for a few years.
If you are not averse to using store-bought herbicides, these provide another option for getting rid of nutsedge. There are three things to keep in mind when spraying yellow nutsedge with an herbicide:
Choose the Right Herbicide
If you will be spraying on a lawn, you need a selective herbicide, not a non-selective herbicide such as Round-Up. A non-selective herbicide kills everything, including your grass; the right selective type will target the nutsedge and leave your grass alone.
Not just any selective herbicide will do, such as an herbicide that targets broadleaf weeds in general. Popular products on the market right now geared to fighting yellow nutsedge contain, as active ingredients, halosulfuron-methyl or sulfentrazone, for example. But it is easier for the homeowner simply to shop for an herbicide whose label says it is effective against nutsedge. Also, follow the label instructions for application carefully.
Use a Surfactant to Aid the Herbicide
For weeds that have a waxy coating on their leaves, such as yellow nutsedge, it is a good idea to use a surfactant when spraying. A surfactant is a substance used in conjunction with an herbicide to make it more effective at penetrating foliage with a waxy coating. You can buy commercial surfactants, but dish soap will also work and is cheaper. Mix a bit of dish soap into the herbicide before spraying.
The idea behind using a surfactant is that an herbicide must stay in contact with the leaves of the targeted plant long enough to penetrate, and a surfactant enhances such contact. A surfactant is thus indispensable when spraying a weed with foliage that is protected by a waxy coating, helping the herbicide grab onto the weed and remain there long enough to do its damage.
Proper Timing for Spraying
When you spray and how often you do so are important considerations. Always spray when there is little to no wind and when the forecast predicts no rain in the immediate future. The best time to spray is in late spring or early summer, when the plants are still young and tender. Make an initial application, wait 1 week, and then apply again. Spray the herbicide directly onto the yellow nutsedge plants. Since yellow nutsedge is difficult to get rid of, you will need probably need to repeat this procedure for 2 to 3 years.
What are some other characteristics of yellow nutsedge?
As the flower heads mature into seed heads, they brown up at first but then may become coppery. Technically, these seed heads (fruits) are called "achenes."
What are some non-invasive alternatives to yellow nutsedge?
Yellow nutsedge is largely lacking in ornamental value. But if you find some mild attraction to its foliage and flower clusters, grow papyrus, instead. Papyrus has much more ornamental value and is not invasive in the North because it totally dies off in winter.
Why is the plant called "nutsedge?"
The "nut" in "nutsedge" refers to the fact that the tubers of some types of Cyperus are grown as a food product (the taste has been compared to almonds) and bear some resemblance to small nuts.