If you’ve planted grass seed on your lawn, you’re probably eager to know how long it will take to germinate. The truth is that there are many different factors that can impact grass seed germination time, so while most lawn grass species have a specific range of days listed on the bag, the germination time for your seed may be different.
In this article, I will discuss all of these factors to help you get a better understanding of when your seed should start to grow.
I’ll also list the average germination times of different popular grass seed varieties, with some tips about when each type of seed tends to grow best, and the conditions each finds favorable.
Let’s get started with the basics of how different types of grass germinate.
Cool-Season Grasses Have Rapid Germination
Overall, cool-season grasses tend to germinate more quickly than most warm-season grass varieties.
If you live in the cool-season grass region (or, in some cases, the transition region) of the United States, you can plant a cool-season grass variety.
Refer to this grass zone map to understand your growing region and select the best type of seed for your lawn.
To make sure your grass will germinate properly, plant it correctly and take care of your newly planted seed. You should plant cool-season grass seed when the soil is around 50 to 65 degrees Fahrenheit. These ground temperatures exist when air temperatures are somewhere between 60 and 75 degrees.
Whether you’re planting and growing a new lawn, or overseeding a cool season lawn, fall is the best time of year (because your seedlings don’t have to compete with annual weed pressure).
If you take correct care of your newly planted lawn, you should see your cool-season grass seed grow and be ready to mow within about one month. These grasses typically germinate within a week and can reach three inches in height within a few weeks of germination.
For example, tall fescue germinates in between 7 and 12 days. Annual and perennial ryegrass germinate very quickly (in between 5 and 10 days – though I’ve seen germination in 3-4 days in perfect conditions). Kentucky bluegrass will usually germinate between 14 and 30 days (making it the cool season grass which takes the longest to germinate).
What about Warm-Season Grasses?
As mentioned earlier, warm-season grass varieties tend to take longer to germinate. It takes longer for warm-season grass seed to germinate and for root development to take place.
There are a few reasons for this, but the process of photosynthesis and growth differs between the two grasses, so if you’re growing a warm season lawn from seed, you’ll need some patience.
If the weather turns cool after you seed warm season grass varieties, it could ruin the germination process. You should wait for the soil temperature to be between 60 and 75 degrees Fahrenheit before you plant warm-season grass seed. The temperature during the day should go over 80 degrees on a consistent basis. Late spring or early summer is typically best.
If you plant a warm-season grass, you will probably see the blades get tall enough for cutting within about eight weeks of planting. Don’t be surprised if you wait a full year to see a dense, lush lawn.
The germination time for buffalo grass is between 14 and 30 days. For Centipede grass, it’s between 14 and 21 days. If you plant Bermudagrass, you can expect germination to happen between 10 days and a month. With Zoysia grass, seeds germinate within 14 and 21 days.
Factors that Impact Germination
While the type of grass seed you plant is the primary factor which impacts grass seed germination time, there are also environmental factors that affect this timeline.
- site preparation,
- the time of year, and
Let’s take a closer look at how each will impact the germination time of your grass seed.
Most grass seedlings thrive in full sunlight. When the seeds sprout, tiny leaves appear and they start harnessing sunlight to generate energy. This energy is essential for leaf and root development.
Your grass seed and the grass that grows will have the best chance of staying healthy and enjoying optimal growth if you have full sunlight, though there are some grasses that grow well in shade.
It’s best if the area where you’re planting gets a minimum of six hours of direct sunlight every day. If it doesn’t have this much sunlight, you will probably need to get a seed mix made especially for shade.
You’ve got to prepare the soil before trying to plant grass seed. If you don’t, your seed isn’t likely to germinate and grow successfully.
You should also try to get rid of any lawn weeds.
If you end up using any chemical weed killers on your lawn, check to see if there is a period you need to wait before planting your grass seed. If you plant the grass seed too soon after using a chemical weed killer, it may adversely affect or even kill the seed.
And if you’re planning to seed in the spring and use pre-emergent herbicide on your lawn (you can find my favorites here) to block annual weed seed germination … be aware this can block grass seed germination too. You can find one option that may work on my list of recommended pre-emergent products.
Carefully read all the instructions on your grass seed to find out exactly what you need to do to prepare the soil before seeding.
Once you have spread the grass seed, use a little bit of straw mulch, or a thin layer of compost or peat moss (about a quarter inch) to cover the area. While grass seed can grow if not covered, I recommend covering it to keep the seeds moist, and protect them from hungry birds.
Keep foot traffic off your lawn after planting grass seed.
If you want your grass seeds to germinate and grow into a healthy lawn, you have to water properly. In fact, giving your grass seed the correct amount of water and watering your seed at the right time is probably the most significant step you can take to create a healthy lawn.
Start watering on the same day you plant your grass seed. You should then water the area every day, keeping it up until germination takes place.
Once germination happens, your goal should be to maintain a moist soil surface. Be careful when watering, not getting too carried away and accidentally dislodge seeds with the water or create run-off.
You should water the area lightly four times every day from the day of planting to when you see germination. Once you see germination, do one half-hour watering session each day, two if it’s especially dry or windy.
You don’t want your young seedlings to dry out.
Once you’ve passed the 22nd day after germination, water the area for 40 minutes every other day.
About a week after that, go to doing a 45-minute watering three times each week.
As your young grass becomes established you want to focus on deep, infrequent watering.
This will encourage your new grass to grow deep roots that seek out moisture between irrigation sessions, producing a lawn that’s more resilient to drought.
Expert Recommendations for Success
Debra Ricigliano is a Maryland Certified Professional Horticulturist at University of Maryland Extension Home and Garden Information Center. She emphasizes the importance of soil testing.
Getting into the details, Debra explains that “Soil testing provides important information such as pH, nutrient levels, and amount of organic matter (most labs test for ths as part of the basic soil test).”
The results of your soil test will tell you what soil amendments are needed. Remember that you want to get the soil in its best possible state before you plant your grass seed. As Debra points out, “After your lawn is planted it is difficult and costly to go back to make improvements to the soil.”
When you’re preparing your site for planting grass seed, “Till or incorporate into the top 4-6 inches of soil the amount of lime and fertilizer that was recommended from your soil test results.” It’s important to avoid tilling “soil that is too wet.” Also, Debra warns that overtilling may “damage the soil structure.”
Debra recommends that you “Apply and rake in a 1-2 inch layer of compost if the soil organic matter level is less than 3% (according to soil test results).” Be aware that a “negative aspect of tilling is that it brings weed seeds to the soil surface.”
Chart: Most Common Grass Types and their Germination Rates
In these charts, I’ll share grass seed germination rates for the most common grass types.
Popular Cool-Season Grass Seed Germination Time Chart
|Best to plant in September
|Can thrive in poor soils
|Avoid overly dry or cold soil
|Plant in the fall months
|Best to plant a minimum of 45 days prior to the first frost
|Avoid excessively dry or cold soil
|Fast seedling growth
Popular Warm-Season Grass Seed Germination Time Chart
|Plant in the spring or early summer
|Expect seedlings to be especially tiny at first
|Can thrive in low-nutrition, sandy types of soil
|Make sure soil is well-drained
|Better toleration of cold temperatures than other warm-season grasses
|Can tolerate high levels of salt in the soil, as well as in irrigation water
Getting Your Grass Seed Ready
There are certain steps you should follow to get your grass seed ready for planting.
While you can simply prep the soil, spread your seed, cover it and water it in, some people improve germination rates and results through a process to pre-germinate the grass seed.
I find this works best if you’re doing lawn repairs (it’s tough for large areas).
Jon Peters of Longview Woodworking has a nice short video showing how he does this using fine sawdust from his shop’s table saw:
I’m a big fan of his YouTube channel and if you’re into woodworking at all, I suggest checking it out here.
Common Problems with Germination
If you’ve noticed that your grass seed isn’t germinating when it should, there is probably another issue.
There are several different kinds of problem that people run into quite a bit. Any one of these can impede or prevent grass seed germination.
Let’s take a look at some common reasons your grass seed isn’t germinating below:
1.You Didn’t Plant at the Right Time
Planting your grass seed at the wrong time of year can mean it won’t germinate and grow as it should. For example, if you planted in mid to late fall, temperatures might have fallen too far, or the first frost might have killed your seedlings as they germinated.
Similarly, if you plant too early in spring the ground may not be warm enough for your seed to germinate. There’s a specific soil temperature grass seed needs to germinate.
I typically advise people to seed in spring when the lilacs start to bloom.
2.You Didn’t Use the Right Amount of Seed
Check to find out how much seed is needed for each 1,000 square foot area of your lawn. Different kinds of grass will have different instructions about how much to use for your space. And the type of seeding project (planting a new lawn vs overseeding a lawn) require different amounts of seed as well.
Certain kinds of seed may need as much as five pounds for each 1,000 square foot area, while others may only call for two pounds.
If your seed is coming in thin and patchy, you may have used old seed that has expired or you may have just not used enough seed.
3.You Didn’t Test the Soil
One of the biggest reasons people don’t get the results they want from their yard is that they don’t know what their soil lacks, or has in abundance.
If your test results show that the soil has the wrong pH or lacks certain nutrients that your grass seed need, you will have to solve this problem before seeding. I use and recommend this test kit, which you can also buy on Amazon if you prefer.
4.You Haven’t Watered Properly
Letting your seeds dry out shortly after they germinate is one of the most common ways homeowners fail at their seeding projects.
Those new seedlings are so vulnerable when they first start to grow, and if they’re deprived of the moisture they need to establish themselves, they’ll die quick.
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