Here's When To Plant Grass Seed For Successful Establishment

When it comes to starting a new lawn from seed, timing is critical. Seeds and seedlings require specific environmental conditions for optimal germination and establishment. These needs vary from one species of turfgrass to the next. Understanding when to plant grass seed based on grass type and your location will ensure you get the best coverage.

Why Is Timing Important for Planting Grass Seed?

Grasses begin life as a single root and leaf blade fed by a tiny seed. These small plants are quite vulnerable. When subject to environmental extremes, such as excessive heat or cold, seedlings can struggle to establish, but under the right conditions, grass seedlings grow quite quickly. Like other plants in the landscape, grasses have periods of active growth that align with specific seasons. You’ll have the greatest success establishing your lawn when you match planting time to these active growth phases.

Factors To Consider When Determining the Best Time To Plant Grass Seed

The primary consideration in identifying when to seed grass is the type of grass you are growing. Lawn grasses can be divided into two main types: cool-season grasses and warm-season grasses. Southern landscapes include both types of grasses, with warm-season grasses being the dominant turf type. The best time to seed each type of grass is at the start of their active growth phase, which differs for these two classes of turfgrass.

Cool-Season Grasses

Cool-season grasses include fescue, Kentucky bluegrass, and ryegrasses, which develop during the winter and early spring months. The best time to seed cool-season grasses is in the fall, when air temperatures begin to cool but soils are still warm from months of summer sunshine. The second-best time to seed cool-season lawn grasses is in spring, after soil and air temperatures begin to rise.

Warm-Season Grasses

Warm-season grasses such as zoysia, St. Augustine, centipedegrass, buffalograss, and bermudagrass thrive under warmer temperatures. They put out a flush of growth when spring arrives. The best time to seed warm-season grasses is late spring to early summer, when temperatures begin to warm but seasonal rains are still plentiful.

Location

Your location will further direct when to seed grasses based on regional climate conditions. In general, spring arrives later the farther north you travel. As such, soils will warm later in the year than in more southerly landscapes. Likewise, cool fall temperatures arrive earlier in the north than in the south. As their names suggest, temperature is one of the main factors driving the growth phases of warm- and cool-season grasses. Rainfall patterns also play a role, as rains typically arrive with the shift in seasons. Let’s take a closer look at planting times and the ideal environmental conditions.  

Best Time To Plant Grass Seed Based on the Season

When timing lawn establishment, our goal is to seed when temperature and moisture conditions are most favorable to seed germination and establishment. For warm-season grasses, warm soil is key. Wait to sow seed until soil temperatures are consistently above 65°F. While this generally corresponds to daytime air temperatures around 80°F, you may want to use a soil thermometer for greater accuracy, as soil temperatures can vary based on slope, aspect, and sun exposure. For example, north-facing slopes tend to warm slower than south-facing slopes.

Sowing warm-season grasses in late spring or early summer provides the additional benefit of seasonal rainfall. You can continue to sow warm-season grasses through mid-summer, as seeds germinate well in soils between 68° to 95° F. As a rule, sow warm-season grass seeds at least 90 days before the average first fall frost date for your area to allow plants time to establish. Sowing too late in the summer can expose seedlings to cold temperatures before they’ve had time to fully establish.

Fall is the ideal time to sow cool-season grass seeds which benefit from the relatively warm soils paired with cool air temperatures and abundant rainfall. These seeds germinate best when soil temperatures have cooled to between 50° and 65°F (air temperatures 60 to 85°F), which falls between early-September to mid-November, depending on location. Avoid seeding too late in the season, as seeds do not germinate as well in colder soils. Cool-season grasses can also be sown in early- to mid-spring when soils have warmed to the ideal range, however, fall-sown plants have more time to establish before the heat of summer sets in. Be careful to avoid planting in cold, wet soil in spring.

Tips for Successful Grass Seed Planting

Pick the Right Seed

Successful turf establishment begins with site preparation and careful plant selection. Start by identifying the best turf type for your planting site. Average rainfall, as well as summer and winter temperatures for your location, will direct your selections. Also consider sun exposure, soil conditions, and access to irrigation. When you’ve identified the ideal turf type, purchase high-quality seed for optimal germination. Plan to sow seed at the recommended rate for rapid coverage. Skimping on seed seldom saves money in the long run.

Plan Ahead

A uniform planting bed with ample nutrients is essential to seedling establishment. Plan ahead when preparing your planting site. Conduct a soil test early enough to allow time for you to obtain test results and fertilizer recommendations. Prepare the seed bed by removing existing vegetation, rocks, and other debris. Cultivate the soil as close to planting time as possible and incorporate any fertilizers, organic matter, and other amendments based on your soil test. Work these into the upper 4-6 inches of soil, then rake the surface to create a smooth planting bed. This will ensure good seed to soil contact.

Plant Properly

Use a drop spreader to broadcast the seed across the entire planting area. For even coverage, apply half the seed making passes with the spreader in one direction, then apply the second half of the seed in the opposite direction. It can be helpful to mix the seed with sand, Milorganite, or a similar material to help distribute it more evenly. Cover the seed with a very thin layer of soil, approximately 1/8 inch thick, by gently raking the area. Firm the soil around the seed using a weighted lawn roller, which can be rented at most equipment centers. This ensures good seed to soil contact.

Pay Attention to Moisture

Keep the seeded area moist through daily, light waterings for the first two weeks to provide the necessary moisture for seed germination. As seedlings emerge, reduce the frequency of watering and practice deeper irrigation. Do not allow the soil to completely dry during the first few months as the grass seedlings establish roots.

With proper timing and care, you can establish a healthy, vigorous lawn in a single season. Getting the timing right will ensure rapid germination and plant development. It can also save you money by making the most of the seed you purchase and reducing irrigation costs by taking advantage of seasonal rainfall. For the greatest success, fine-tune your seeding times to match the specific turf type, aligning these to local environmental conditions.