Overseeding Your Lawn
Time Required: 2-4 hours
Overseeding is an important part of growing a healthy, lush lawn. Overseeding revives damaged plants caused by a lack of water, heavy foot traffic and heat. Overseeding not only allows grass to grow where it doesn’t exist, but it also improves the entire stand of grass by sowing better varieties. The process of overseeding involves planting grass seed directly into the existing turf without ruining the turf or soil. If you don’t overseed, you run the risk of weeds overtaking your lawn.
Fall is the ideal time to overseed cool season grasses, because the soil is still warm enough to germinate seeds and the cool air invites grass to grow a strong root system. Cool season grasses include Kentucky Bluegrass, Perennial Ryegrass and Fescue. Warm season grasses include Bermuda, Centipede, Saint Augustine and Zoysia.
Additionally, for tips and helpful information on how to properly feed your lawn, visit our Feeding Your Lawn project guide. And if you're thinking about the best way to go about planting trees and shrubs, check out our 10 steps to Plant a New Tree and Shrubs project guide.
Your geographic location affects when and how you overseed. Cooler fall weather happens earlier in the North; therefore, you should overseed your cool season grasses by late summer or early fall if you live in this region. Late spring or early summer is ideal for overseeding warm season grasses in the South.
There are a few things to keep in mind before you overseed:
- Make sure you know the measurements of your lawn. Multiply the width and length of your lawn space to calculate the square footage. If you have multiple areas to cover, divide each section and do the calculation, and then add the sums together for the total square footage.
- Stop fertilizing for at least a month before overseeding. Vigorous growth of the existing lawn will make it more difficult for the new seeds to establish themselves.
- Identify your grass type, so you can treat it appropriately. To do this, examine the climate of your growing region, look at the shape of the grass blades, feel the texture of the grass, and/or take samples to your local Home Depot Garden Center for assistance.
- Consider doing a soil test if you don’t know the pH level of your soil. This will help you determine the conditions of your soil, so you can apply the appropriate nutrients to it. Test your soil using a soil test kit or take samples to your local extension service or state university to analyze.
Tools & Materials
- Mow your lawn so that the grass sits above the soil line. Ideally, it should stand at an inch to an inch and a half. This will allow your grass seed to get adequate sunlight and connect with the soil.
- Next, use a thatch rake or power rake to remove any thatch that you find, a process called dethatching.
- Thatch is a spongy layer of dead organic matter mixed with living plant parts that can lead to disease and insect problems if not eradicated. A heavy layer of thatch can prevent your grass seeds from germinating.
- To dethatch, rake the lawn in one direction and give it another pass in the opposite direction. The tines on the rake will pull up the thatch along the way. Be sure to rake the thatch off the lawn when you’re done.
- Another way to remove thatch is to aerate your lawn. This combs your grass and kicks out debris. It also loosens the soil so that air and water can reach the roots. Your grass seed will be able to grow faster and more robust. Lawns that are compacted due to heavy foot traffic should especially be aerated to produce efficient growth.
- A core aerator is a great tool for this job. You can rent one at your local Home Depot store.
- To operate the core aerator, move it across the lawn in straight lines until the yard is fully covered. Do a second pass perpendicular to the first one if needed. Make sure the core aerator pulls plugs of soil from the turf rather than simply punching holes in the ground. This helps to break up the compaction. Leave the plugs to dissolve on their own within a couple weeks.
- If your lawn has bare areas, spot treat it with topsoil, which will improve the quality of the soil and allow the grass to grow.
- For areas with water drainage problems, typically where the grass doesn’t grow, apply a thin layer of sand over it and smooth it out with a rake. Sand allows the grass to germinate faster and it creates a thicker root zone.
- Now you can spread your grass seeds evenly around the lawn using a broadcast spreader, drop spreader or hand spreader. Follow manufacturer’s instructions for distributing the seeds.
- Then, apply slow-release fertilizer that works best for your specific grass. Slow-release fertilizer provides nutrients to plants gradually, within three months in many cases. This will prevent you from over-fertilizing.
- Lightly water the lawn immediately after overseeding. Continue to water it frequently, about three to four times daily for the first several weeks to ensure proper germination.
- Once the grass is an inch tall, cut the frequency of watering back to once a day, but increase the duration of watering to 20 to 30 minutes per zone.
- Continue to mow the grass to a height of two inches for the remainder of the season. Mow the lawn when the grass is dry.
- Fertilize the lawn about six weeks after you sow the seed. Apply a pound of quick-release nitrogen fertilizer for every thousand square feet of lawn space.
- If your lawn is 5,000 square feet, you would need five pounds of quick-release nitrogen fertilizer to treat it. The fertilizer should work for your specific grass type. Repeat this process in another six weeks.