Solved! The Best Time to Plant Grass Seed
Dreaming of a lush lawn? The trick to successful sowing is a clear understanding of your type of grass and the climate it thrives in.
Q: I’d like to lay some grass seed this year, but I don’t want to get the timing wrong and create more work than necessary. What’s the best time of year to sow a new lawn from scratch?
A: More than anything else, when to plant grass seed depends largely on the climate in your part of the world and the types of grasses that thrive there. Next, consider the actual forecast around that time to select the best time to seed a lawn. Most Americans want to be surrounded by green lawns they can spend time in, and a few factors come into play to ensure the grass seed put down takes root.
Grass Seed Generally Falls into 2 Categories: Warm-Weather and Cool-Weather Varieties
The best turf success comes from planting the right grass for the region in which you live. You might consider water and care needs and appearance. But selecting a grass not meant for your climate can erase some of those benefits. Grass is categorized by season, so choose based on when it thrives: cool season or warm season. Each of these varieties requires different maintenance and—you guessed it—minimum sowing requirements to grow good-looking grass from seed.
- As you might imagine, warm-season grasses (including Bahia grass, Bermuda grass, centipede, and St. Augustine) thrive in climates with mild winters and hot summers and don’t require as much water as other grasses. They germinate and grow in temperatures above 80 degrees.
- Cool-season grasses such as bluegrass and ryegrass fare best in places where summers are temperate and winter days often dip below freezing. Requiring more hydration (often delivered via snowfall), these varieties lie dormant in warmer summer months and do most of their growing in autumn and spring.
- If you live in an area that falls between those two climate zones, you’re in a transitional region. Cool-season grasses (with late summer/early fall preparation) are more likely than their warm-weather cousins to flourish in a zone that falls between the extremes, but you can plant a mix of both—cool-weather grass sown in late fall and warm-weather planted during the spring and summer months of the following year.
- Grass can thin over time, requiring you to overseed the lawn to fill in. You can mow the existing turf shorter than normal, prep the ground, and sow grass seed to fill in. Overseeding also works best when temperatures support germination for the grass type chosen.
- Consider your neighborhood’s altitude and the USDA Plant Hardiness Zone. If you’re still unsure which type of grass matches your climate, do some local research. This list of university extension programs might help you look for the safest choice and best time to plant grass in your area. Or consult local nurseries or hire a landscape professional.
When is the Best Time to Plant Grass Seed?
The short answer is to match your timing to align with the natural course of a grass type’s active growth. That means when to sow grass seed depends on optimal temperatures for their germination. Of course, there is more to consider than just temps in your timing.
- Take care not to distribute your seeds just before heavy rains, which can erode the soil and disrupt germination. (Sowing right after it rains is fine, but dry soil is generally easier to seed.)
- Specific timing can get tricky for both seasons. The best time to plant warm-season grass seed is late spring or early summer, or when temperatures hover near 80 degrees or higher in your area.
- Plant cool-season grass seed in late summer or early fall (when daytime temperatures lower to about 60 to 75 degrees) for best success. September is typically the best month, although you might be able to get away with seeding as early as mid-August or as late as mid-October; it all depends on the forecast.
Time When You Plant Grass Seed Well After You’ve Last Applied Herbicides
If you use chemical treatment on your existing lawn to control weeds, wait at least a month after the treatment before you lay down new grass seeds. If you’ve used a crabgrass prevention product, the recommended waiting period is even longer—usually around 4 months.
Ideally, plan your lawn maintenance well in advance so that you can wait the appropriate amount of time between treating a lawn and when ideal temperatures for seed germination typically set in. If you didn’t save yourself enough time to weed before seeding, know that you can resume your weed prevention routine once your new lawn has been mowed at least four or five times.
Pay Attention to the Weather When Planting Grass Seeds
You can plan ahead for the best time to put grass seed down based on average temperature patterns in the area, but it helps to check the forecast to pinpoint the best time to plant grass seed. Make sure you won’t have an unusual cold snap or heat wave.
Likewise, watch for rain events. While a good soaking can help seeds germinate, a downpour can cause seeds to erode or migrate, gathering in a bunch at the bottom of a hill, for example. And it is best to plant grass seed before a steady rain, not right after a heavy one. Muddy ground is hard to work and too much moisture around new seeds could lead to a fungal disease that kills the seeds.
Seeds still can germinate in cloudy weather, assuming temperatures are near suggested levels for the grass seed you choose. It’s probably best not to seed the lawn on a windy day, which can affect broadcasting of seeds or blow just-set seeds around if not tamped down.
Scheduling Your Seeding Depends on When You Have the Time to Prep the Soil
Whether you seed or sod a lawn, allot time on your calendar for a bit of prep work as the time draws near. This might require some pretreatment with an herbicide, and that month or more of waiting. You can also simply remove all weeds with hoes and by hand.
Starting with bare ground? Loosen the top 2 inches of soil and remove any materials (i.e. sticks and stones) that could block airflow. If you’re broadcasting grass seed over a large, bare area, a seed spreader and light tiller might come in handy. Hard ground might first require aeration or loosening soil a little deeper, closer to 6 inches.
Otherwise, if you’re working with an existing lawn that just needs some rehabilitation, take the weekend to mow it as short as you can. Then loosen up the soil in any bald spots.
Next, no matter whether your lot is bare or simply balding, inspect that the surface is as level as possible and add fresh topsoil wherever it dips; this helps prevent puddles of standing water once you begin the irrigation process. With this prep work under your belt, you’re ready to begin sowing grass seeds—and soon enjoying a lush lawn.
Time Other Activities That May Affect the Seeding of Grass
Planting grass seed is one of the least expensive ways to a lush lawn or to fill in a large bare area of weeds or blowing dust. Still, the seeds and their early growth (seedlings) need a little tender loving care early on.
Typically, you should avoid walking on the new lawn area for at least 4 weeks. Any activities from kids or dogs on the growing lawn can disturb your carefully broadcast seeds. Once the seeds germinate, the seedlings are tender as they grow above and below the ground, establishing roots. Walking on seedlings can damage them or uproot them.
So, avoid kids’ birthday parties or training a new puppy within a month of setting seed. Avoid mowing until the seedlings reach at least 3 ½ inches high; the longer you can wait, the better.
How Long Will It Be Before You See Results?
Time from planting to picnicking on a new lawn can vary depending on the specific seed type (some grow faster than others), site prep, seed quality (and age), and unpredictable factors like weather. In general, cool-season grasses grow faster than warm-season ones. Most cool-season grass seeds should begin to germinate in 5 to 7 days. Popular warm-season grass seeds usually take nearly 2 weeks and as long as 3 weeks. Be patient; a few factors can affect germination, such as:
- How well you prepped the area, loosening soil, leveling, removing rocks and weeds, and mulching lightly.
- Unseasonal dips or peaks in temperature, even in the evening, that can affect soil temperature and seed germination.
- Lack of sunlight; seeds can germinate in cloudy weather, but seedlings need some sun (6 hours a day or more) to help them grow and spread to form turf. Grass seed planted in shady areas of the lawn might take longer to germinate.
- Irrigation, especially too little, affects time to germination. Seeds need steady moisture to sprout, and do best with water sprayed lightly on the soil surface. Over-irrigating to the point that water pools or runs is nearly as bad as drying out. Spray seeds several times a day for the first few weeks, depending on the weather.
FAQ About When to Plant Grass Seed
Will grass seed grow if I just throw it down?
Yes and no. Native grasses, in particular, will likely sprout in some areas, but there is a difference between sporadic sprouting and a broad area of seeds taking root. Just throwing seeds out will likely lead to uneven coverage. Plus, the blades that might pop up will not be healthy, well-rooted grass without adequate site preparation. If you want to speed up the process, try asking a lawn care professional to hydroseed your lawn.
Is March too early to plant grass seed?
In nearly all regions, March is too early to plant grass seed. Temperature is a better barometer; wait until days average about 80 degrees before planting grass seed for summer. March is too late to sow cool-season grasses.
Do you need to rake in grass seed?
Once you spread the grass seed, use a rake to work it into soil, but only to about ¼ inch. Don’t push the seed down too deeply or cover it with a thick layer of mulch that will block light. If you can, use a roller to pass over the area after raking to ensure seeds have good contact with soil. You can sprinkle a light layer of compost or straw over the soil to help retain moisture, but only thin enough to prevent blocking light.
Should I soak grass seed before planting?
It’s not necessary to soak grass seed before planting; the seeds are small and typically germinate 1 to 2 weeks after planting with consistent watering. If you have a short window for the best time to seed a lawn, especially for getting cool-season grass going before cold sets in, you can soak the seeds in water for 24 hours. Then, drain the water completely from the cup or bucket, and leave them in a warm location like a heated shed for a few days until small sprouts appear.