When to Plant Grass Seed in Spring for Best Results

Springtime is when many of us start planning improvements and rejuvenating our homes. If you own a house, this also probably means taking care of your lawn and garden. If you need to plant grass seed in spring, it’s important to plant your grass seed at the right time. Whether you’re growing an entirely new lawn or simply filling in empty or sparse areas, you want new grass established before annual weed pressure but after the soil is warm enough.

In this article, we will discuss the best times in spring to plant your grass seed for the best possible results.

After all, timing is essential to get the lush and beautiful lawn that you deserve.

Why is Timing So Important?

Don’t underestimate just how important timing is for successful grass planting. This is because the correct conditions are necessary for the seed to properly germinate, grow, and retain its health.

Spring tends to be a good time of year for planting many different kinds of grass due to the season’s combination of rain, sunshine, and warming temperatures, but it poses challenges to grass seedlings as well.

A spring-planted lawn has to contend with pressure from annual weeds and its young root system will need support to survive the heat and drought of a tough summer.

Additionally, many homeowners rush and plant grass seed too early in spring before soil temperature catches up with the air temperature.

So, When Should I Plant Grass Seed in Spring?

You need to plant grass seed in spring after soil temperatures are at least 55 degrees Fahrenheit, and before annual weeds begin growing (because they’ll smother your new grass). You also need to plant your spring lawn early enough that its root system can develop sufficiently to survive the heat and drought conditions of summer.

All of these factors make starting a lawn in spring tough for lawn care beginners. You have a narrow window of a week or two, so you have to be ready.

You can have success, but the odds are stacked against you so it’s all about execution. This is why many people (especially in northern climates) prefer to wait until late summer or early fall. Soil temperatures are already high from the summer, annual weeds are beginning to fade, and your cool-season grasses will thrive in the cooler temperatures of fall, developing a robust root system to over-winter.

But this is an article about planting lawns in spring, so I’ll stay focused on that topic and do everything I can to help you succeed.

Local conditions make a huge difference for when plants grow.

It’s best to get advice from lawn care professionals in your area to know the best time to plant new grass, but I’ll offer some general guidance to help you succeed below.

Let’s start with tips for different types of grasses (northern grasses and southern grasses).

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Cool-Season Grasses

If you have a cool-season grass, you should plant your grass seed when average temperatures during the day are between 60 and 75 degrees Fahrenheit. In these temperatures, soil will likely reach the right temperature levels for the optimal germination of cool-season grasses.

Cool-season grasses should usually be planted in early spring or (ideally) in fall.

If you plant in spring, you don’t want it to be too close to summer. That’s because the heat of summer will be extremely hard on seedlings, and your new lawn will also have to compete with pressure from annual weeds like Crabgrass.

There are pre-emergents for crabgrass that you can use, but some will prevent your seed from germinating. For brand new lawns, I recommend using this starter fertilizer + crabgrass preventer from Scotts. It’s a quick-release fertilizer that allows your seed to germinate while blocking crabgrass germination and it’s what I use whenever I plant grass seed.

If you plant in the fall instead, you need to make sure there is enough time before winter.

Warm-Season Grasses

Warm-season grasses, like Bahiagrass, Zoysia grass, Centipede grass, or Bermudagrass, should ideally have grass seed planted in the early summer rather than the fall.

Don’t plant warm-season grass seed until the average temperature during the daytime is at least around 80 degrees Fahrenheit.

It’s especially important to ensure that there is absolutely no chance that there could be another frost. If you want to plant warm-season grasses in spring, you will probably need to wait until late spring.

How to Prepare Your Soil for Grass Seed

While spring is a great season to plant grass seed, you’ll need to take other steps to ensure success.

No matter how careful you are about when you plant your grass seed, if you don’t have properly prepared soil, there is little chance that you’ll end up with a beautiful lawn.

Your seed needs good contact with your soil to germinate, and it also needs to be kept moist (but not wet) so that it doesn’t dry-out.

There are generally three good ways to prep your existing lawn’s soil for seeding in spring:

• Use an iron rake to loosen the topsoil and remove dead grass and weeds (recommended for small areas)
• Use a power rake or dethatcher along with a core aerator to provide plenty of soil contact and water/air penetration of your topsoil (recommended for whole-lawn overseeding projects and thick lawns with heavy clay soil)
• Try renting a seed slicer to cut furrows into your topsoil for your new seed (recommended for thin lawns in sandy soil)

Additionally you should …

Make Sure Your Lawn is Level

Before you plant your grass seed, ensure that the site is appropriately graded. This is necessary to ensure proper draining of water and fixing drainage issues now will make it easier for you to mow, as well.

A slope in the lawn in the opposite direction of buildings is recommended. This should be very slight, at just a 1 or 2 percent grade. It’s better to stay away from anything steeper than that, as it would make your lawn lose moisture too rapidly, and steep hills can make it dangerous to mow.

You should also eliminate depressions in your yard, by smoothing it out thoroughly. Depressions are something to be avoided because wet spots can collect in them and this can lead to disease and tricky mowing.

An uneven lawn can be a hazard for people walking over it, too. Top-dressing your lawn at the time of planting grass seed is what I recommend.

When Replacing a Lawn Altogether, Remove All the Old Grass

Don’t be sloppy with the details if you’re killing an existing lawn and starting over. The whole thing must be removed. Don’t leave any of the old turf behind.

You’ll need a sod cutter to help you properly remove the roots of the old grass.

Alternately, some people kill and remove old lawns by applying a non-selective herbicide. Remember to be careful in how you use this, carefully following the product directions and apply this well in advance so that none lingers behind at the time of planting your new grass seed.

Some weed killers are safe to use on lawns, but many herbicides will kill every kind of plant. Carefully keep it away from things you want to stay alive. You may need to apply this more than once to kill all of your old grass.

You can get rid of the dead grass afterward, and then see to the grading and smoothing of your lot before planting your new lawn.

Conduct a Soil Test

Getting your soil tested will tell you how healthy your soil is – which nutrients it has in abundance, and which nutrients it is lacking.

Not only will this allow you to ammend your soil properly prior to planting grass seed, it will save you money on your fertilization all year long.

Many people throw down bag after bag of high-nitrogen fertilizer when their yard is already rich in nitrogen, but may lack iron, microbes, or minerals that will make the nitrogen more accessible to your plants.

I think of it like serving big bowls of spaghetti to dinner guests but not giving them a fork to eat it with.

You’ll need to take samples of your soil, then send them for tests. You can purchase a soil test kit from your local garden center, extension office, or online.

I use this soil test kit from Amazon every year and love the results which are saved in my online dashboard so I can not only see how my yard’s soil is now, I can monitor it for changes over time and see that my fertilization program and amendments are working.

It’s the best money I spend on my lawn every year and I highly recommend it to all homeowners who are serious about improving their lawn.

And if you’re interested in taking the guesswork out of what to do next after you get your soil test results, consider Sunday’s subscription lawn-care plan. They test your soil for you and use local weather data to send you exactly what your lawn needs, when it needs it. It’s pretty fool-proof – you can Click Here for Your Instant Lawn Analysis and take 15% off your order with promo code LAWNCHICK2024.

Adjusting Your Lawn’s pH Levels

Remember that grass needs a specific pH range in the soil in order to thrive. This is why you should test your soil’s pH level. Your local hardware, box store, or garden center will carry these and they will run you a few bucks. You can find them on Amazon as well.

The majority of lawn species prefer soil between 6.0 and 7.5 pH.

If your soil has the wrong pH for the kind of grass seed you are using, you will need to adjust it with soil amendments.

• With excessively alkaline soil, you can apply elemental sulfur.
• Apply lime if your soil is overly acidic.

This will help with nutrient availability. Remember to be very careful about how you use all products.

Take time to read the instructions provided on the product packages, as misusing products can cause damage to your lawn and create more work.

When applying lime or sulfur to adjust your lawn’s pH level, I always recommend that you under-apply vs. over-apply. You can always come back and add more later if needed.

Apply Fertilizer to Add Nutrients

Once you have done this, you will need to provide your soil with the extra nutrients it needs.

Look for a higher quality lawn fertilizer that matches your soil’s test results, and if you aren’t sure what to use I highly recommend this Scott’s starter fertilizer for Spring planting. It works great for new lawns, and I typically follow it up about 3-4 weeks later with an application of Milorganite, an organic, slow-release lawn fertilizer.

Be aware that many localities regulate what you can and cannot apply to your lawn due to pollution and runoff concerns.

This is especially true for Phosphorous, one of the key ingredients in starter fertilizers (because it supports root growth).

Before applying any fertilizer to your yard I encourage you to research your local rules so you know what you can, and cannot apply to your lawn.

In my experience, your local extension office is the best place to start.

Aerate Your Soil

Many homeowners will benefit from aerating their soil prior to seeding in the spring, especially if it is compacted, heavy, or primarily clay.

Aeration is crucial because it allows more air and water to get down into the soil and to the roots of the grass.

When prepping your lawn for seed, you should also get rid of any rocks on the ground.

After aerating and overseeding, I do recommend covering your grass seed so it doesn’t dry out. Peat moss or screened compost applied with a roller like this one on Amazon are my recommendation, but lots of people use straw.

Whatever you choose to use as a natural mulch for your new grass seed to keep it moist (and away from hungry birds), be sure the material you use isn’t filled with weed seeds.

Understanding Germination of Grass Seed

How long it takes for your grass seed to germinate depends on the type of seed you used. The period may vary from between 5 and 21 days.

If you’re spreading Kentucky Bluegrass you may not see any signs of germination for 3 weeks. Some Fescue grasses and Perennial Rye may germinate in a matter of days.

Consistent watering at the right times of day is critical to your success in the first few weeks after spreading grass seed in the spring.

With some grasses you’ll be able to mow your new lawn in 2 weeks, with others it could be months before it’s well established and ready for foot traffic.

My advice is to be honest about how much time you’re willing to commit to babying your new lawn. Personally, I like seeing results quickly, and I want to be able to let my kids loose on my lawn within a month. That informs my decisions when I’m choosing grass seed.

Fill in Bare Spots in Your new Lawn

After you notice that seedlings are about one inch tall, check your yard closely to see if there are bare spots in the area.

Between seed getting washed out and inconsistency with your spreader, it’s possible that you missed some areas and have some bare patches. You can now add seed to these spots, and go through the whole process again for them.

Filling in bare spots while your soil is still well prepared for your seed and your watering schedule is well underway is essential if you want your lawn to look green, lush and beautiful.

Final Thoughts About Planting Grass Seed in Spring

When you plant grass seed in spring is more important than during any other time of year.

Spread your seed too early and it won’t germinate (but will feed hungry birds).

Spread your seed too late and competition from annual weeds and the dog days of summer will likely overwhelm your new lawn.

But if you pay attention to soil temperature, use the right starter fertilizer, water well, and follow-through, you can enjoy a beautiful spring-seeded lawn all summer and for years to come.

Good luck!