On established lawns, following a balanced fertility program, regular mowing cycle, and proper irrigation practices can keep weeds from encroaching. Lawns in North Dakota are basically a Kentucky bluegrass blend or mixture, tall fescue blend, or in the drier parts of the state, a cultivar of crested wheatgrass, buffalograss, or blue grama. Generally the shorter the grasses are mowed, the greater the weed problem. A minimum mowing height should be no less than 2.5 inches, with 3 inches preferred for Kentucky bluegrass blends and mixes and tall fescue blends. Allowing the clippings to fall when mowing will help recycle nutrients and reduce the need for fertilizer applications.
Nutrient maintenance is necessary to keep the lawn vigorous.
Too much nitrogen, which stimulates shoot growth at the expense of root development, actually weakens the turf, making it vulnerable to weed encroachment. Irrigation practices, which put the applied nutrients into solution and move them into the root zone, can set the stage for weed development if not properly managed. Anything less or more may allow weeds to establish. Look for signs of initial wilting before applying water. A dark, bluish-green color and footprinting are signs that the turf is in need of water.