Keeping a lawn weed-free is not impossible, as many homeowners may conclude. You can, with a bit of work, kill those unwanted pests. Then, by keeping the sun from shining on the ground, you can continue to keep the weeds at bay. Accomplish this by mowing the grass more often and at the highest setting. In addition, seeding or adding sod to your lawn so that the grass is thick and plush will also help shade the ground so the weeds cannot germinate and grow.
Kill perennial weeds such as clover, thistle and dandelions while they are actively growing. The best time is late summer or early fall before they prepare for the winter by storing energy in their roots for the next growing season. Alternatively, try in the spring to slow down their growth, which may kill them.
Avoid mowing a couple days before and after applying your herbicide.
Apply an herbicide, following manufacturer directions carefully. Choose an herbicide designed to kill perennial (or broadleaf) weeds. Apply evenly and use a granular spreader for granular herbicide or a calibrate sprayer for liquid herbicides.
Determine if you have perennial or annual grassy weeds. If necessary, take a sample to your local nursery or university extension office.
Remove perennial grassy weeds (such bluegrass and quackgrass) manually. No herbicide works on these. Use a spade or shovel to remove individual patches. It’s easiest when the soil is wet; be sure to remove the roots.
Remove annual grass weeds (such as crabgrass and foxtail) with an herbicide before the grass starts growing in the spring. This could be as early as late winter in some areas. Sometimes, herbicides are mixed in with fertilizers. Be sure the herbicide is labeled for annual grass weeds or as a pre-emergent herbicide and follow application directions carefully. In addition, wait the required amount of time before reseeding your grass, if necessary.