Most lawn weeds are opportunists that take root wherever they can find the space and catch a few rays of sunlight. These interlopers stand little chance of establishing themselves in healthy grass. That's why a sensible lawn care plan will help stop weed problems before they have a chance to start.

Fertilize enough, but not too much. Too little fertilizer can lead to sparse lawn that loses the competition with weeds. Too much helps nurture certain weeds, notably annual bluegrass, Bermuda grass and crabgrass. Strike a balance by following the application rates on the package. And use a fertilizer with a high percentage of controlled-release nitrogen, such as sulfur-coated urea, ureaform or IBDU. These provide a slow, steady nutrient supply.

The frequency and timing of your fertilizing efforts are also crucial to healthy lawns. Both vary depending on your lawn type and the length of your growing season. Most northern lawns need only one or two applications of fertilizer annually—once in fall and sometimes a second time in spring. Southern grasses might require three feedings—early to midspring just after the grass greens up, early summer and again in early fall.

Water grass infrequently and deeply. Frequent, light watering causes shallow roots and helps annual bluegrass, crabgrass, chickweed, sedges and other weed seeds germinate. If you water too little, the lawn suffers while spotted spurge, Bermuda grass, quackgrass and other weeds adapted to drier soil thrive. Instead, provide your lawn with infrequent, deep soakings. Lawns need about 1 inch of water per week. Set an empty tuna can on the lawn to determine when you have applied 1 inch of water.

Mow higher. Mowing too low weakens turf by reducing the ability of a grass leaf to produce enough nutrients. It also lets light hit the soil surface, which helps crabgrass and goosegrass seeds sprout and grow. Check with your local extension service for the recommended range of mowing heights for your grass type. Then mow at the highest level—usually between 2 and 4 inches.

Learn to read weeds. Sometimes weeds are a clue to soil or site problems. Correct them so your landscape favors lawn grasses and discourages weeds. For example, ground ivy grows best where the soil surface remains damp. It also thrives in areas too shady for good grass growth. So consider improving soil drainage by aerating—removing small cores of soil—if ground ivy is a problem. And, to allow more light to reach the surface of the soil, selectively remove tree branches in shady areas.
Ask TOH users about Lawn Care

Contribute to This Story Below