To prepare the soil after either method, make sure you till it down to roughly 6 to 8 inches.
Applying the right amount of seed is key. As a general rule of thumb, apply roughly 15 seeds per each square inch, then rake over the seed.
Weeds come in multiple categories, either broadleaf, grass-like, or grassy.
Step 5: Rake and Till
Keep in mind that herbicides can kill whatever plant life they come into contact with—even if the label says otherwise—so handle with care. If your aim is to re-establish your lawn, as we recommend, killing your existing, thinning grass isn’t a big deal, since you will need to start fresh anyway.
Weeds can be broken down further into categories based on their life cycle—annual, biennial, or perennial.
Read our handy guide on how to restore a weedy, patchy lawn to its former glory.
If your lawn is patchy and full of weeds, it will never be the envy of the neighborhood. What you’re after is a lush, green lawn with even grass and no dandelions poking their way through. That may sound hard to achieve, but it isn’t too difficult if you follow these steps.
Chemical weed preventers, also called preemergent herbicides, are usually granules or liquids, but both require water to work. As the preventer soaks into the ground, it leaves a residual film in the top 1-inch of soil. Because most seeds germinate at or just below the soil’s surface, these preemergent herbicides remain active against any germination processes for up to four months, depending on the chemicals involved. Organic weed preventers work in a similar way. With many weeds being members of the grass family, all seeds, including desired lawn species, fail to germinate and sprout after you’ve used a weed preventer.
Spreading seed is an inexpensive way to grow a lush lawn, but exposed soil between germination and establishment makes it vulnerable to weeds. Although chemical weed preventers have different mixtures and instructions, you should not apply them while seeding or immediately afterward. You must allow one to four months between applying this type of chemical and spreading seed.
Avoid the need for weed preventers by keeping your lawn healthy. Once established, only water your turf once a week during the growing season. Up to 1 inch of water during this watering session allows roots to search deeply for moisture to create strong grass. Shallow grass roots die in stressful conditions, like drought, and allow weeds to grow in thinned spots. Allow your turf to grow to a healthy height as well, typically between 1 and 3 inches, depending on the species. Long grass blades mean the grass can produce enough energy to stay healthy and compete with weeds. In short, healthy and well-maintained grass has less problems with weed growth.
Even if you time your weed preventer and seeding periods correctly, you need to do the job right to get an even lawn with no bare patches. Apply seeds uniformly across your yard using a drop spreader on a mild fall day. Spread up to 1-inch of organic mulch over the seeds to conserve moisture and encourage germination. Water the seeds at least twice a day for short, 10-minute sessions. You do not want to wash away the seeds, but they need consistent moisture to grow. Hand pull any weeds that appear while the grass seedlings develop. Do not apply any chemicals for weed control.
Cool-season grasses are usually seeded, as opposed to warm-season grasses that usually need to be grown from sod or plugs. Because cool-season grass seeds germinate best in fall, apply your chemical preventer in spring to actively kill off weeds in spring and summer. In general, temperatures between 65 and 70 degrees Fahrenheit are good for weed preventer application. Hot days often cause the chemicals to vaporize into the atmosphere, reducing their effectiveness. By the time fall seeding weather arrives, the chemicals are no longer active and the grass seeds will be able to sprout.
Perennial grass most active during cool spring and fall seasons.