Q. Mike: I've been battling nutsedge in my lawn for 5 years. This stuff is tough. I am thinking about getting a flame weeder and burning it out. Any better ideas?
- ---Ben in Center Valley, PA
- ---Leslie and Gary in suburbs of St. Louis
- ---Tim in Pennington, NJ (near Princeton)
- ---Worth in El Dorado (way down in South AK, 15 miles from Louisiana)
Unfortunately, this appears to be more truth than hyperbole. A true sedge and not a grass, it reproduces by rhizomes, seed, and the underground tubers from which it gets its 'nutty' name. There are over 600 species in its genus ("Cyperus"); the big weedy ones are yellow and purple nutsedge. Yellow has lighter colored leaves and one tuber per rhizome. Purple has darker leaves, a 'chain' of tubers on each rhizome and is considered a much worse weed. (The colors in the names refer to the 'spikelets'; what passes for flowers on these kinds of plants.)
The most famous Cyperus family member is papyrus. And this aquatic plant from which paper was first made reveals the biggest problem that makes this weed welcome: Excessive soil wetness. As with all lawn weeds, the problem is generally with the lawn more than the weed, and this is no exception. These plants LOVE constantly wet feet and are often found in overwatered lawns with poor drainage.
If your lawn, like so many, was sown on unamended crappy soil, aerate the turf to get some drainage going—the real way, with a machine called a core aerator pulling out plugs. Then apply corn gluten meal as a natural 'weed and feed' in the Spring to give your grass a good feeding and prevent the seeds from germinating. (Make sure the CGM is labeled as a pre-emergent herbicide; the 'animal feed' kind probably won't be high enough in protein to work on those seeds.)
Other feedings of the turf should be with compost, to help improve soil structure. (Read a few of our PREVIOUS QUESTIONS OF THE WEEK on lawn care and bulk compost for more info on this important subject.)
In his recent book "The Organic Lawn Care Manual", Paul Tukey notes that nutsedge is a sign of low calcium levels; so have your soil tested and add lime or wood ash as recommended. And everyone agrees that this weed thrives in anerobic (low oxygen) soils. Paul recommends using compost tea to introduce more life to the soil; Howard Garrett prefers molasses. I say feeding with bulk compost should do it.
And if you're watering your lawn frequently, cut back! Oy! Read our Previous Question of the Week on wise watering and don't be afraid to let your turf go dry at times.
Now, because it does grow so much faster than grass, this nutty weed gives its location away easily. So yes, burning the top growth repeatedly with a flame weeder (or smothering it with an herbicidal soap spray or attacking it with a vinegar based herbicide) will force the underground tubers to resprout and use up a great deal of their energy; one soil scientist says up to 60%. Thus, repeated attacks on the top will eventually starve the underground tubers. But while some sources say that four attacks on the above ground growth (wait until at least six new leaves are showing) will do it, others say it takes a dozen. (Read through some of our PREVIOUS QUESTIONS OF THE WEEK on weed control for lots more info on the controls we just mentioned.)
Removing those underground 'nuts' is the best answer, but they are recalcitrant, and no one gives hand-pulling any hope of success. Luckily, ducks, geese and guinea hens will unearth and eat the tubers for you! Otherwise, use a poaching spade to exhume the nuts. Or experiment with a mechanical weed-puller designed to remove dandelions, like the Weed Hound; you'll see right away if it pulls out those little tubers. Either way, you'll be getting some aeration in the deal. Fill the holes with compost.
If the whole lawn is a weedy mess, use this as a reason to start over; early fall for cool season lawns in the North; Spring for warm season grasses down South. Plan ahead so you can till it all up and then let it sit until the nuts dry out. (Or run some fowl in there—they'll make short work of exposedtubers!) Then screen out what nuts you can and replant overtop of a good two to four inches of high quality compost. That'll insure good drainage, lots of soil life and maybe smother some of the bits left behind.
Or eat the nuts! The tubers of yellow nutsedge are so edible the plant is known as the "Earth Almond" and its grown professionally. One source says they taste like almonds; the USDA says "between fresh coconut and raisins". (The purple variety is bitter and used in Oriental Medicine). So harvest your nuts—and tell your neighbors: "That's not a weed, it's a cash crop!"