A sedge that will drive you nuts

Bob Dluzen
Special to The Detroit News

A nefarious weed is trying to stake out a claim to part of the garden. That weed is the dreaded nutsedge, sometimes called nutgrass, so called because it looks a little bit like grass. The “nut” part of the name comes from the small nut-like bulbs, sometimes called nutletts, that develop on roots as the plants grow.

If you look closer at its stem, you can see it’s not a grass. Grass stems are round at their base while sedge stems have a triangular cross section. One thing for sure though, if it gets in your garden, you’ll learn the difference very quickly.

Once established, nutsedge is one of the most difficult weeds to get rid of. The primary method of reproduction is from its underground structures.

Nutsedge plants produce two kinds of underground reproductive structures. In the fall they produce tubers which are able to survive the winter. It is from these overwintering tubers that we get our spring plants. Tubers are easily spread during tillage.

In the spring, as the newly emergent plant grows, it sends out underground rhizomes  that grow laterally. At the end of each rhizome a small nutlett bulb forms which then immediately begins growing and sends out its own rhizomes. This process continues through spring.

This nutsedge has sprouted from tubers. Notice how much larger and more aggressive growing they are compared to the weed seedlings growing with it.

Another but less common reproductive method is by seed. Like other plants, mature nutsedge plants produce seed but the tiny plants are not very good competitors so are not as likely to survive the battle against other weeds.

Certain soil conditions are more inviting to nutsedge than others. They prefer damp soil that has low porosity which leads to a larger population of anaerobic microorganisms. Often the soil is low in calcium, but not always.

Changing the soil conditions such as providing adequate drainage, whenever possible, will reduce the chance of nutsedge moving in. Also, it is critical not to till soil when it is too wet, doing so will destroy soil structure and reduce the porosity.

These young nutsedge plants have long roots originating from tubers present deep in the topsoil.

The best way to control nutsedge is to attack them early before they make much growth. Repeated hoeing will cut the tops reducing  photosynthesis. It works fairly well on small plants like the ones I found.

Any type of cultivation that will bring the nutletts or tubers to the soil surface so they will be exposed and  baked in the hot sun is the best control method to use in the garden. Fortunately, the vast majority of nutlets are in the top 6 inches of topsoil.

Certain herbicides are on the market that purport to kill nutsedge but I avoid these, especially in the vegetable garden.

Laying sheets of heavy black plastic mulch will kill the growing nutsedge by blocking out sunlight.

Back in the olden days, farmers discovered pigs love to eat nutsedge nutlets and will root up an area looking for them.

My plant is to start cultivating now and keep it up all through this growing season and probably through the next.

Nutsedge tubers are able to live in the soil for up to three years or more and can send up shoots from deep in the soil, so I’ll have to be vigilant for the next few seasons.