Green Kyllinga

What is green kyllinga?

Green kyllinga is a low, mat-forming perennial sedge that has become a serious weed of lawns, golf courses and landscape beds across the southern United States. It is easily mistaken for a nutsedge or a fine grass, so green kyllinga identification comes down to a short checklist: triangular stems, very fine leaves, a round green seed head and no tubers. A near twin, false green kyllinga, looks almost the same, and Extension guides group the two together for control.

Its rhizomes can stretch more than an inch a day in warm weather, knitting a thick mat within weeks, and one plant can make up to about 5,000 seeds in a season, even when mowed as low as 3/4 inch. In turf it leaves a weak, spongy, off-color surface that looks ragged within two days of mowing; in beds the mats crowd out desirable plants.

Green Kyllinga identification: what to look for

Get down at lawn level and study a single shoot. Kyllinga leaves are finer than any nutsedge, the flowering stems are three-sided, and the seed head is a tight green ball rather than an open spray. Lift a piece of the mat and you will find shallow runners linking the shoots, but no tubers.

• Leaves: Narrow, flat, hairless and shiny dark green, usually about 1 to 6 inches long. Run a fingernail along the edge and you will feel tiny barbs.
• Stems: Flowering stalks are triangular in cross section and about 2 to 8 inches long.
• Seed head: One dense, globe-shaped green head roughly 3/8 inch across, with three leaf-like bracts radiating just below it. Each head holds 30 to 75 tiny spikelets.
• Seeds: Flat, oval and tan, only about 1/8 inch long.
• Rhizomes: Creeping underground stems root at each node, and any piece with a node can start a new plant. There are no tubers.
• Growth habit: A continuous, expanding mat much like a creeping turfgrass, unlike the scattered individual shoots typical of nutsedges.
• Winter color: Stays green in mild-winter areas; where winters are colder it goes dormant and fades to yellowish, brown or purplish brown.

Where it grows in the United States

Green kyllinga is a warm-climate weed, reported from Florida across the Southeast to Arizona, California and Hawaii, and North Carolina State Extension notes it has overrun turf in parts of the Southeast. In California it ranges from San Diego north into the Sacramento Valley. Its look-alike, false green kyllinga, tolerates more cold and is the more common of the two in the mid-Atlantic, where it is moving north.

It does best in full sun on wet or overwatered ground, such as low spots, poorly drained lawns and heavily irrigated areas, though established mats can handle some shade and drying. Bermudagrass lawns are hit most often, but it also invades cool-season turf, athletic fields, landscape beds and ditches. Mowers, foot traffic and cultivation carry seed and rhizome pieces around a property.

Green Kyllinga look-alikes

A few plants get mixed up with it:

• False green kyllinga (Kyllinga gracillima): Nearly identical, and often called green kyllinga too. It is more cold tolerant, so it is the likelier of the two in the mid-Atlantic and farther north. For a homeowner the difference rarely matters, because the same practices and herbicides handle both.
• Purple nutsedge (Cyperus rotundus): Wider, coarser leaves, an open reddish-purple seed head instead of a green ball, and chains of tubers on its runners. Nutsedges also tend to come up as separate shoots rather than a solid mat.
• Yellow nutsedge (Cyperus esculentus): Wider, light green leaves, an open yellowish seed head, taller growth and a single round tuber at the tip of each runner. Kyllinga never forms tubers.

How to get rid of green kyllinga

Pulling, digging and mowing: Hand-pulling and hoeing seldom work unless you keep at them for a long time, because any rhizome piece left behind can regrow, and hoeing followed by watering can actually spread it. The best physical option is to dig out each patch with a shovel, taking the surrounding soil, then refill and replant. Grubbing out a lone new plant early works well if you watch the spot for several months afterward. In beds, organic mulch alone will not stop it, but landscape fabric laid with overlapping seams and covered with bark or wood chips, plus hand removal of anything that pokes through, gives good control. Mowing does not control it.

Cultural control matters most, because the right conditions keep it from coming back.

• Stop overwatering: adjust irrigation so wet spots dry out, and improve drainage in low areas or cut back the water they receive.
• Keep turf and groundcovers dense so they shade the soil and seedlings cannot get a start.
• Mow at the higher end of your grass's range. In a University of California study, mowing hybrid bermudagrass at 1 inch instead of 2 inches increased kyllinga germination and growth.
• Fertilize properly; extra nitrogen helped newly planted turf fill in and slowed kyllinga's spread.
• Clean mowers, aerators and tillers before moving from an infested area to a clean one.

Herbicides: Herbicides work best combined with water management and keeping new plants out. To stop seedlings in lawns, preemergence active ingredients such as benefin, bensulide, dithiopyr, pendimethalin and prodiamine go down in spring before the soil reaches about 60°F; oryzalin and pendimethalin serve the same role in ornamental beds where labeled. They do little against established plants. For existing mats, selective postemergence options include halosulfuron, sulfentrazone, imazosulfuron and trifloxysulfuron. Virginia Tech lists sulfentrazone and halosulfuron among the most effective homeowner choices, and University of California work found halosulfuron worked best as two sequential applications, the second made when plants start to recover. Treat young, actively growing plants in early to mid-summer. Glyphosate spot treatment also kills the surrounding lawn, so plan to reseed or sod. Choose a product labeled for your turf species or planting, and follow the label, which is the law. If you hire someone to spray, make sure they hold your state’s pesticide applicator license; the rules for each state are in our pesticide applicator license guide.

Keeping it from coming back

Green kyllinga travels mostly on equipment and in soil. Clean mowers and tools after working in infested turf, watch new sod and plantings for its fine leaves and round seed heads, and dig out any lone plant, rhizomes and all, before it becomes a mat.

Its seed sprouts at or near the soil surface once the soil reaches about 65°F, so dense turf and mulch help a lot; in one Arizona study, burying seed just a third of an inch deep cut germination about twelvefold. Pair that with sensible watering and good drainage.

Questions we get about green kyllinga

Similar weeds

Purple NutsedgeCyperus rotundusYellow NutsedgeCyperus esculentusBahiagrassPaspalum notatum