This Grassy weed Is Not Technically a Grass; It's a Sedge and Is Very Difficult to Control
Nutsedge, also known as nutgrass, is a perennial, grass-like weed that seeks out the moist, poorly drained sections of your yard or garden and grows faster in hot weather than our lawns. Its leaves are grasslike and yellow-green, while the spiky head is purple or yellow. It's a tough weed to control because it grows from tiny tubers, or nutlets, that form on roots that can grow 8-14 inches deep in the soil. Pull out the roots and some tubers will stay behind to grow. Individual nutsedge plants may eventually form patches of 10 feet or more in diameter.
Mow High to Help Control Nutsedge
Depending on your turf type and latitude, you can help control nutsedge or nutgrass by changing the way you mow. Mowing your lawn at the proper height, which in most cases is one of the 2 highest settings on your mower, lets the grass crowd out nutsedge and other weeds. Mowing short stimulates nutsedge.
You can help prevent nutsedge by regularly feeding your lawn with Scotts® Turf Builder® Lawn Food. A healthy, maintained lawn is the first defense against nutsedge. A well-fed lawn grows thick and is better able to crowd out weeds. If you're seeding a new lawn, you can prevent yellow nutsedge for up to 6 weeks by applying Scotts® Turf Builder® Starter® Food for New Grass Plus Weed Preventer.