Yellow Nutsedge Wins Community Garden Weed of the Year Award!

Yellow nutsedge is the grasslike weed that is easily pulled, tricking you into thinking you have done it in.  What is not apparent is what's happening below ground.  The nutsedge has emerged from a little brown storage organ called a tuber.

When the 'grass' portion is removed, the little root breaks off leaving the tuber in the ground.  As long as that tuber is in the ground you will find the grasslike portion emerging again and again.  One tuber was buried over 5" and sent up a slender thread to emerge as a tiny nutsedge with the signature 3 leaves.

If you continue to pull the nutsedge when it is little, you will eventually exhaust the nutrient supply of the tuber and it will stop producing its vegetation above the soil line.

If you wait until the plant has matured, you have allowed the underground portion to multiply with many tubers.  Each will produce its own plant next May when the soil temperatures remain above 43ºF.

You may notice around this time of year the nutsedge flowers emerging.  While the main way of propagating itself is not through its flower seeds, if you have let it seed up, this means that there are tubers attached to the mass of delicate roots maturing below. Buds on the tubers or nutlets sprout and grow to form new plants; thus individual nutsedge plants eventually form patches that can range up to 10 feet or more in diameter.

The tuber is the part of the plant that survives the cold of winter.  If you want to get rid of a nutsedge infestation, then you have to remove the tubers.

How do you get rid of the tubers or 'nutlets'?

The majority of tubers can be found in the top 6 inches of soil where they can survive for 1 to 3 years.  When you go to remove the nutsedge seedling or clump, dig carefully around and down under the plant.  Clemson Cooperative Extension recommends digging “at least 10 inches deep and at least eight to 10 inches beyond the diameter of the above ground leafy portion of the plant.”   OR You can start early in the summer and every 2-3 weeks remove the emerging nutsedge seedlings before they have a chance to make new tubers.  This will force the mature tuber to keep producing until it exhausts itself.

Cornell Cooperative Extension recommends enclosing the tubers in a black plastic bag and leaving them to bake in the sun.  Do not put them in the compost pile!

There are uses for these tubers.  They are edible (soak first) and said to have a slightly sweet, nutty flavor.  They are sometimes known by their Spanish name, chufa. They are also known as Tigernuts and have a rich mineral content. The British boil them and use as bait for carp.

More about the nutsedge

Don’t let the leaves fool you. They superficially resemble grass but are thicker and stiffer than most grasses. Notice that the leaf is V-shaped in cross-section, not flat. They also emerge in sets of three from the base rather than sets of two like grasses.

This perennial plant, an indicator of poor drainage, thrives in waterlogged soil but once established can survive and persist with no irrigation.

Removal or eradication strategy after the plant has emerged, whether by hand weeding or herbicide applications, is most successful if done prior to the longest day of the year, June 21.  (When tubers are mature there is little translocation of a herbicide from the leaves to the tuber.  Of course, in an organic garden, no herbicides are allowed!)

NB: According to ATTRA, "... sweet potatoes have been shown to inhibit the growth of yellow nutsedge, velvetleaf, and pigweed. Field trials showed a 90% reduction of yellow nutsedge over two years following sweet potatoes."