How to Overseed Your Lawn

It's no secret that a thick, healthy lawn reduces the need for using water and fertilizer. Today's grass varieties have been developed to have a greater resistance to insects, drought, and disease. They're also designed to stand up to heavier foot traffic. If your lawn is starting to look thin and tired, and the weeds are starting to creep in, it may be time to give it a boost by overseeding it.

• Mow it. The real key to getting grass seed to germinate is getting the seed in contact with the soil. To help facilitate this, mow your grass on the lowest setting possible without scalping the lawn. If your mower has a bagger attachment, pick up the clippings and toss them on the compost pile.

• Rake it. After your mow, the entire yard needs to be gone over with a metal rake. This step is labor intensive, but don't skip it. Raking will rough up any exposed soil (creating more surface area for seed contact) while removing thatch, grass clippings, and any remaining debris.

• Choose the right seed. Find out what type of mix is optimal for your yard. Look for mixes that are 100% weed free (even though it's unlikely they really will be). If you're presented with a choice between hulled or unhulled seed, you will get more hulled seeds for the money because you're not paying for the weight of the hulls. Both types germinate equally well.
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• Spread the seed. This can be done with a hand-held broadcaster or a walk behind drop spreader. Hand-held models work great for smaller lawns and are available at most hardware stores and big box garden centers for $20-$40. Use the broadcast rate recommended for new lawns. This will help make up for seed that is washed away, fails to germinate, or is eaten by birds. Using approximately 1/2 the seed, make the first pass in strips across the lawn. Then using the remaining seed, take a second pass across the lawn at a slight angle. This will help ensure you get full and consistent coverage.

• Rake in loosely. After you spread the seed, go over the yard lightly with a metal rake to knock any seeds stuck in the grass down to the soil.

• Top off with 1/4 inch of compost. Covering the grass seed with a little bit of topsoil does three things: it adds organic nutrients to the old soil, it helps keep the seed moist after watering, and it hides the seed from hungry birds.
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• Water in well and keep moist. Once moistened from the first watering, the seed should never be allowed to dry out until it fully germinates. This can take up to two weeks and may mean watering twice a day. Germination rates can drop by as much as 30% if you miss even one day so stay on top of it. Once the old grass reaches 3 inches tall you can mow again (medium height). This will give any late germinating seeds more light. After 4-6 weeks, the new grass should be well established.