What is Overseeding?
Overseeding is the planting of grass seed directly into existing turf, without tearing up the turf, or the soil. It’s an easy way to fill in bare spots, improve the density of turf, establish improved grass varieties and enhance your lawn’s color.
If a lawn looks old, or just “worn out,” if it needs growing amounts of water and fertilizer to thrive, or is disease or insect prone, it’s a perfect candidate for overseeding.
- Fill in bare spots
- Improve turf density and color
- Helps lawn withstand insects, disease, drought, shady conditions, and heavy traffic
- Reduce the amount of fertilizer, water, and pesticides required
You must analyze the problems that caused the original turf to deteriorate. It might be due to conditions that, if not corrected, will eventually cause the overseeded lawn to deteriorate, too. The main thing is to correct the problem before you establish new grass.
The Overseeding Process
Seeding should be done in a crisscross pattern and at a consistent depth for the lay of seed to germinate and root properly and evenly throughout the area planted. Inconsistent lay and depth can result in bald spots and a higher level of weeds. A powered turf seeder is the most efficient and effective way overseed and get a healthy lawn with rich, thick turf.
Do This First
For established turf with bare or weakened thinning areas, professionals tend to dethatch and overseed at the same time. Dethatching first to remove any matted thatch and then overseed. Doing both allows for the best possible penetration of seed and root establishment to quickly thicken up the turf.
The Right Equipment
For small to moderate-sized lawns or larger flat areas, a standard turf overseeder like the Classen TS-20 walk-behind turf seeder is a fine choice as the unit will be lighter in weight and easier to control. For large areas or hilly terrain, the self-propelled Classen HTS20 overseeder will limit user fatigue and get the job done quicker. An overseeder with a floating seed box will offer the best possible seed coverage. It will hug the terrain and maintain consistent seed drop, ensuring tight pattern seed coverage on hills, over undulating or choppy terrain.
Late summer or early fall is the best time to overseed lawns. Soil and atmospheric temperatures are most favorable for optimum seed germination and growth. With adequate moisture, fertilizer and sunlight, the new seedlings will be well established before cooler fall weather sets in. Also, weed competition is less of a factor at this time, giving the grass seedlings a better environment to grow and develop.
Spring overseeding risks the chance of weather-related problems (heavy spring rains, unexpected high temperatures) and weed competition. Also, spring seeding may interfere with the application of preemergent crabgrass or broadleaf weed killers; concurrent application of seed and herbicides is generally not recommended because the herbicides may cause poor seedling establishment. It is best to delay herbicide treatment 4-6 weeks after new grass seed germinates. If you choose to overseed in the spring, be sure to follow proper seeding and treatment practices.
Midsummer overseeding faces greater chances of disease, heat and drought stress, and weed competition. Proper weed control and adequate irrigation are musts if overseeding is attempted in midsummer.
Depending on conditions and type of seed, new grass seed will begin to emerge in 5-7 days after seeding when moisture and soil temperatures are adequate. An overseeded lawn can be fully established in eight weeks or less.
Proper watering is critical to successful overseeding. The following is a recommended watering program.
- Immediately after overseeding: Water heavily to wash grass seeds into slits.
- Until grass seeds germinate (first 10-14 days): Water lightly on a daily basis, soaking first one inch of soil.
- After germination: Water less frequently, but allow for deeper soaking and penetration into soil. This encourages deeper root growth.
- After grass becomes established: Water at the recommended level for the type of grass planted.
The key is care and patience. Proper overseeding will produce a healthier, better looking lawn that responds better to mowing, fertilizing and watering. An added benefit is increased property value!