When to plant grass seed – for the perfect lawn

Knowing when to plant grass seed is important if you want to grow a healthy lawn.

Having lush, green grass is integral to most people’s backyard, but whether you are after how to plant grass seed from scratch, or trying to fill in patches in grass to make a lawn green and thick, you need to time it just right.

‘With the rise in prices of grass seed over recent years, it is critical to maximize your success when timing planting,’ says Adam Gore, horticulture agent for Clemson University Cooperative Extension.

‘This means it is vitally important to seed a lawn during optimum growing conditions. Doing so will reduce the risk of disease development, poor seed germination and seedling failure.’

When to plant grass seed

Considerations for timing

When to sow grass seed depends on several factors: soil temperatures, the expected weather forecast, grass species selection and location.

Local climate

Your local climate is a particular factor if you want to minimize the risk of seedling-related diseases. Gardeners in the warmer south may find they can plant their seed earlier than those in cooler northern areas. 

Grass types

However, the type of grass also plays a part.

‘Just as every person has a difference in temperature preference so too do grass species,’ says Gore. 

‘Warm-season grasses – such as Bermuda grass, zoysia grass and centipede grass – prefer to have soil temperatures at or above 65°F (18°C) for best germination, whereas cool-season grasses – such as tall fescue and ryegrass – prefer soil temperatures below 65°F (18°C).'

Weather

‘Just as crucial is the weather that follows. Any seedling requires conditions that favor their germination and growth. Exposing a plant to the extremes of harsh summers or winters can lead to eventual failure of the grass due to the plants not having the proper amount of time to establish.’

If you’re in a hurry to get your new lawn off to a good start, then choose from the best fast-growing grass seed, and finish it off with one of the most stylish lawn edging ideas.

When is the best time to plant grass seed?

The best time to plant grass seed depends on the type of grass you are growing.

‘It’s generally best to plant cool-season grass seed in early fall and warm-season grass seed in late spring,’ advises Jeremy Yamaguchi, CEO of Lawn Love.

‘While you can technically plant it any time of the year, these specific times have the best ground moisture and highest likelihood of precipitation while the weather is still mild to warm. These are the most optimal conditions for grass seed and will yield the most desired results.

What is the best month to plant grass seed?

The best month to plant grass seed does vary from zone to zone: in northern zones, it might be late August or September; in southern zones, in October or November. The grass seed likes warm soil but cooling temperatures. When conditions are like this, it is the best time to plant grass seed.

When to plant grass seed in spring

Warm-season grasses should be planted in the spring for the best chance of success.

‘These grasses need time to establish an acceptable root system before dealing with the extreme temperatures that may come with summer or winter,’ says Gore.

‘Planting in mid-to-late spring allows these seedlings the most hospitable environment that encourages growth prior to any of these environmental stresses.’

Meanwhile, cool-season grasses can be planted in the late winter to early spring. ‘Though an early spring window may experience greater risks as planting at this time may not allow sufficient plant maturity before summer stress occurs,’ adds Gore.

When to plant grass seed in the fall

Cool-season grasses are best planted in the early fall, allowing them plenty of time to establish before the following spring.

‘Cool-season grasses develop deep root systems that can allow them to survive the cold winter months,’ says Erinn Witz, co-founder of Seeds & Spades.

‘Plant the seeds when temperatures are between 50-65°F (10-18°C).'

FAQs

• Thorough preparation is key to successful grass seed planting. ‘Testing your soil for nutrient levels is an often-overlooked but crucial step in getting healthy new grass to grow,' says Witz. 'If your test shows any significant nutrient deficiencies, correct them before planting.' This could involve adding a liming product or nutrients via fertilization.
• Prepare the ground to be planted by removing stones and debris, and raking over the area to ensure it is as even and finely textured as possible.
• ‘Use a handheld or broadcast spreader to apply your seed and use a lawn-starter fertilizer to supply a nutrient boost,’ says Witz.
• ‘Immediately after seeding, the area should be lightly raked, top dress, rolled or drugged over with a mat or similar device, to ideally encourage what is referred to as “seed-to-soil” contact,’ adds Gore.
• Consider laying straw or hay over the area afterward to prevent the loss of seed from birds and washouts from rain.
• Water lightly everyday until your seeds germinate, then water less frequently but more deeply for the next few weeks.