Overseeding After a Hot Summer: How to Get a Thicker Lawn

Fills In Bare Spots

Overseeding is the process of spreading grass seed over an existing lawn. It helps fill in bare spots that heat stress, and possibly lawn disease, leave behind in the hot summer months.

Improves Density

New seed improves the density of the lawn. It is especially important for lawns with thin or patchy areas from wear and tear, pests, or disease, and it makes the yard look fuller.

Builds a More Resilient Lawn

Overseeding introduces new, healthier grass varieties. That makes the lawn more resilient to weather conditions, foot traffic, and other environmental stressors.

Helps Resist Weeds

Overseeding is not a cure for severe weed infestations, so it is best to address those first. After that, overseeding can help thicken the grass and create a more robust lawn that is better equipped to resist future weed growth.

Early Fall Is the Ideal Time

For cool-season grasses, the ideal time to seed is early fall, typically from late August to early October. The soil is still warm enough to promote seed germination, and the cooler air temperatures help reduce stress on the new grass.

Why Not to Seed in Spring

Seeding in the spring means planting during the time of year when weeds are growing the fastest, so the new grass has to compete with them for room. In the fall, the seed has plenty of time and room to germinate.

Extreme Temperatures and Drought

Avoid seeding during extreme temperatures or during periods of drought. These conditions can harm seed germination and growth.

Deal With Weeds First

If your lawn has a significant weed problem, address it before overseeding by using weed control treatments or manually removing weeds. This gives the new grass the best chance to grow without competition from weeds. Lawn Buddies offers a lawn prep treatment for weeds, usually done about 3 to 4 weeks before aeration and seeding.

Water and Mow for the Heat

During the summer heat, water deeply and infrequently, about 1 to 1.5 inches of water per week, in the early morning. Set your mower blades to the highest setting, typically around 3 to 4 inches for cool-season grasses, and keep them sharp. Taller grass shades the soil and helps it retain moisture.

Check for Pests and Soil Problems

Inspect the lawn for signs of pests like grubs, chinch bugs, and sod webworms, and treat infestations promptly. A soil test shows nutrient deficiencies and pH levels, so the soil can be amended as needed.

1. Mow Shorter and Rake

Start by mowing the lawn shorter than usual to allow better seed-to-soil contact. Then rake the area to remove debris, leaves, and dead grass that could block seed from reaching the soil.

2. Aerate the Soil

Aerating creates small holes in the ground. It helps improve seed-to-soil contact and allows oxygen, water, and nutrients to penetrate deeper into the soil. This is especially important if the soil is compacted. If the lawn has a lot of thatch, dethatch it too.

3. Consider a Starter Fertilizer

Consider applying a starter fertilizer rich in phosphorus to support seed growth and root development. This helps encourage strong, healthy grass.

4. Spread the Seed Evenly

Follow the recommended seeding rate listed on the seed bag. It is a good idea to divide the seed into two equal portions and apply one in one direction and the other at a 90-degree angle. A broadcast spreader is typically the easiest and most accurate way to spread seed.

5. Water Lightly Right Away

Immediately after seeding, water the area lightly to settle the soil and ensure good seed-to-soil contact.

The First Couple of Weeks

Water 2 to 3 times a day, but use a light touch to avoid washing away seed or creating puddles. The goal is to keep the soil surface consistently moist but not soggy.

Once the Grass Is Growing

Once the grass begins to germinate and the seedlings start to establish roots, reduce watering to once a day or every other day, depending on weather conditions. After the grass has grown to about 2 to 3 inches tall, you can switch to watering deeply but less frequently to encourage deeper root growth. Generally, it is better to water early in the morning to reduce evaporation and minimize the risk of disease.

Mowing and Birds

After an aeration and seeding, it is advised that the lawn not be mowed for at least 4 weeks. Watch for birds as well. Birds love seed, and a significant number of them in the yard right after seeding can leave bald or patchy spots. Lawn decoys, sprinklers, and anything that makes noise help keep them away.