Plant grass seed in spring after the last frost, when soil temperature reaches 50°F and stays there

Spring grass planting works because soil is warming, moisture is available from rain and snowmelt, and cool nights slow evaporation. The exact timing depends on where you live — in the upper Midwest and Northeast, that's typically mid-April to early May; in the mid-Atlantic and upper South, late March to mid-April; in the lower South and Southwest, February to March. Check your local frost date first, then wait until soil temperature at 2 inches deep stays at 50°F or above for at least three consecutive days. A soil thermometer costs $8 to $15 at any garden center.

Spring planting does have a trade-off: grass planted now will compete with weeds all summer, and if a hot, dry spell hits in June or July, young seedlings can struggle. Fall planting (September through October in most regions) avoids this, but spring works fine if you're willing to water and manage weeds for the first 6 to 8 weeks.

Key Takeaways

  • Wait until soil temperature reaches and holds at 50°F before planting, which usually happens 1 to 2 weeks after the last frost date in your area.
  • Prepare the soil by removing debris, breaking up compacted spots, and raking smooth — seed needs direct contact with soil to germinate.
  • Spread seed at the rate printed on the bag, using a broadcast spreader for large areas or hand-spreading for small patches, then rake lightly to work seed into the top quarter-inch of soil.
  • Water lightly every day or every other day for the first 3 to 4 weeks until grass is 2 to 3 inches tall, then switch to deeper, less frequent watering.
  • Mow for the first time when grass reaches 3 to 3.5 inches, cutting only the top third of the blade to avoid shocking young plants.

Prepare the soil before spreading seed

Grass seed germinates only where it touches bare soil. Walk the area and remove sticks, stones, old thatch (dead grass buildup), and any debris. If the soil is hard or compacted, use a garden rake or a dethatcher to break it up — you're aiming for a loose, crumbly surface about a quarter-inch deep. Bare patches or low spots should be raked level so water doesn't pool.

If you're overseeding an existing lawn (filling in thin or bare spots), mow the grass short first — about 1 to 1.5 inches — so seed makes contact with soil. Rake vigorously to pull up dead grass and open the soil surface. For a completely bare area or a lawn that's more than 50 percent bare, you're doing a full renovation, which follows the same steps but covers the whole space.

Test your soil pH if you can — most lawn grasses prefer 6.0 to 7.0. A soil test kit costs $10 to $20 at a garden center, or your county extension office can test a sample for $10 to $30. If pH is off, amending it now (before planting) is easier than trying later. Most spring plantings don't need fertilizer before seeding; the seed itself contains starter nutrients, and you'll feed the lawn once it's established.

Choose the right seed blend for your region and sun exposure

Grass seed bags are labeled by region and light condition — cool-season mixes for the North, warm-season for the South, and shade blends for areas under trees. Read the label and match it to your location and the amount of sun your lawn gets. A lawn that gets 4 or more hours of direct sun needs a full-sun blend; 2 to 4 hours needs a partial-shade blend; less than 2 hours needs a shade blend. Planting the wrong type wastes money and effort.

The bag also lists the seed rate — the amount of seed per 1,000 square feet. Measure your lawn (length times width, minus any buildings or hardscape), divide by 1,000, and multiply by the seed rate to find how much seed you need. Overseeding uses about half the rate of a full renovation. Buy 10 to 15 percent extra to account for waste and uneven spreading.

Spread seed evenly across the prepared area

For areas larger than 500 square feet, a broadcast spreader (also called a rotary spreader) saves time and spreads seed more evenly than hand-spreading. Set the spreader dial to the rate printed on the seed bag — the dial number matches the bag's recommendation. Walk at a steady pace in straight lines, overlapping each pass slightly so you don't miss strips. For small patches or edges, hand-spreading works fine: pinch seed between your thumb and fingers and scatter it in a thin, even layer.

After spreading, rake lightly with a garden rake to work the seed into the top quarter-inch of soil. You want seed in contact with soil, not buried deep or sitting on top. Rake gently — you're not trying to bury the seed, just nestle it into the soil surface. If you rake too hard, you'll move the seed around and create bare spots.

Water consistently for the first month

Grass seed needs constant moisture to germinate — not soggy, but never dry. For the first 3 to 4 weeks, water lightly every day or every other day, depending on rainfall and heat. A light watering means just enough to dampen the top half-inch of soil; you're not trying to soak it. Early morning is the best time to water, before heat and wind increase evaporation.

Once seedlings emerge (usually 7 to 14 days after planting, depending on seed type and temperature), keep watering lightly until grass reaches 2 to 3 inches tall. Then gradually reduce frequency but increase depth — water fewer days per week, but water longer so moisture reaches 2 to 3 inches deep. This encourages roots to grow deeper and makes the lawn more drought-resistant.

If rain falls, count it toward your watering. Stick your finger into the soil — if it's moist an inch down, skip watering that day. Overwatering can cause fungal disease and waste water, so check soil moisture before each watering.

Mow for the first time when grass reaches 3 to 3.5 inches

Young grass is tender and can be damaged by mowing too early or cutting too short. Wait until grass is 3 to 3.5 inches tall — usually 4 to 6 weeks after planting, depending on seed type and temperature. Set your mower to cut at 2.5 to 3 inches (removing only the top third of the blade). Never cut more than one-third of the blade height at once; cutting deeper stresses young plants and can kill them.

After the first mow, continue watering as needed — soil should stay moist but not waterlogged — and mow every 7 to 10 days as the grass grows. By 8 to 10 weeks after planting, the lawn should be thick enough to handle normal traffic and maintenance. At that point, you can switch to your regular mowing schedule and fertilize according to your grass type and local recommendations.

Manage weeds without harming new grass

Weeds often sprout alongside new grass in spring because the same conditions that help grass germinate help weed seeds germinate. Hand-pull weeds when they're small and soil is moist — they come out easier and you won't disturb young grass roots. Pulling is safer than herbicide for the first 6 to 8 weeks; most weed-killing products can damage tender seedlings.

Once grass is established (usually 8 to 10 weeks after planting) and you've mowed it 3 or 4 times, you can use a broadleaf herbicide if weeds are still a problem. Read the label to confirm it's safe for young lawns, and explore only to weeds, not the whole lawn. Preventing weeds is easier than killing them later — keep the lawn thick and healthy by watering and mowing correctly, and weeds have less room to take hold.

Frequently Asked Questions

Can I plant grass seed before the last frost date?

No. Frost will kill germinating seeds and seedlings. Wait until soil temperature is consistently 50°F or above, which usually happens 1 to 2 weeks after your area's last frost date. Planting too early wastes seed and money.

How much water does new grass seed need?

Light, frequent watering — just enough to keep the top half-inch of soil moist — for the first 3 to 4 weeks. That's usually 10 to 15 minutes with a sprinkler, once or twice daily depending on heat and rainfall. Once seedlings are 2 to 3 inches tall, water less often but deeper to encourage root growth.

What if I plant seed and it doesn't rain?

You must water. Seed needs constant moisture to germinate. If rain doesn't fall within a day or two of planting, water lightly every day until rain arrives. Dry seed will not germinate, and once it dries out, it's dead.

Can I plant grass seed in late spring?

Yes, but the later you plant, the more heat stress young grass faces in summer. Late May or June planting in the North means seedlings are still tender when heat arrives in July. They'll survive if you water consistently, but fall planting (September to October) is easier because cool nights reduce water needs and weeds are less aggressive.

Do I need to fertilize new grass seed?

Most seed bags contain starter fertilizer, so you don't need to add more at planting. Once grass is established (8 to 10 weeks after planting), you can fertilize according to your grass type and local recommendations. Your county extension office can advise on timing and rates for your area.