How Long Does It Take Grass Seed To Grow

There are a number of factors that determine how long it will take grass seed to grow. From the variety of seeds, you choose to sow through to the soil conditions and weather.

This guide will help you understand how long does it take grass seed to grow? We will share expert advice covering the different factors involved, and share how you can help your grass seed to grow better, faster, and stronger.

How Long Does It Take Grass Seed To Grow

From the point, your grass seed is broadcast it will take on average 8 days to germinate. Then the seedling will go through a period of development to put down its roots and form the familiar top growth or foliage.

The top growth will grow at a rate of around 2-3 cm a week depending on the species of grass and many other environmental factors.

Throughout this article, we will look into how long it takes grass seed to grow based on the grass species, the type of grass, and the surrounding conditions that directly influence its ability to grow at an optimal rate.

Grass Seed Germination Rate

How fast grass seed germinates depends on a number of factors including; grass variety, time of year and weather conditions, soil temperature, and moisture. With optimum conditions, grass will on average within 8 days.

Some grass varieties can germinate as quickly as 5 days whilst others can take up to 22 days. In absolutely perfect conditions, some grasses may germinate within 2-4 days. But typically 5 days is considered fast germination in a lawn setting.

Grass Type

The first factor in determining how quickly grass seed will grow is the type of seed you purchase for your lawn. Different varieties of grass seeds will germinate and grow at different rates.

If we assume a grass type is sown at the appropriate time of year for the grass type and growing conditions are good, Annual Ryegrass can germinate within 5 days, whereas Bentgrass can take over 3 weeks. Below is a summary of popular grass types and their germination rate.

Grass Seed Germination Rate in Days

Under ideal circumstances, it takes between 5 and 30 days for grass seeds to germinate, depending on the variety.

  • Bermudagrass germinates in 5 to 10 days
  • Perennial Ryegrass germinates in 5 to 7 days
  • Annual Ryegrass germinates in 5 to 10 days
  • Kentucky Bluegrass germinates in 10 to 21 days
  • Red Fescue germinates in 12 to 22 days
  • Zoysia Grass germinates in 14 to 21 days
  • Bentgrass germinates in 14 days

Of course, the variety of grass is just one of the many factors that affect germination and growth rate. So let’s run through some of the other external or environmental elements that also influence seed germination and grass growth rates.

Grass Germination Temperature Chart

Grass can germinate in temperatures as low as 50 Fahrenheit, however, this is not optimum. For a reliable germination rate temperatures of 59 Fahrenheit or more is optimal for cool-season grass and somewhere in the region of 68 Fahrenheit or above for warm-season grass.

Turfgrass SpeciesOptimum Air Temp F.
Creeping bentgrass59-86
Annual bluegrass68-86
Kentucky bluegrass59-86
Rough bluegrass68-86
Tall fescue68-86
Red fescue59-77
Sheep fescue59-77
Chewings fescue69-77
Perennial ryegrass68-86
Reference: Purdue University

Soil Temperature

Soil temperature and air temperature vary depending on the time of year. In springtime, the soil temperature is behind air temperature, simply as it takes longer to heat through.

However, when it comes to the germination of grass seeds, air and soil temperatures are considered roughly the same as grass seeds sit on top of the soil. So the soil surface temperature is very close to the prevailing air temperature.

How To Speed Up Grass Seed Germination

There are a number of steps that you can take to speed up the germination process and improve you’re germinating rate of seeds.

Prepare Your Soil

All seeds like to germinate in loose aerated soil that is well structured with organic material allowing it to hold moisture. So with this in mind be sure to prepare your planting surface with good quality topsoil. Level it off but be careful not to compact the soil by treading on it.

The looser the soil is the better it will be for holding moisture and allowing the delicate seed root to penetrate down and establish.

Planting grass seen on hard or dry soil will leave the seeds waiting for a downpour of rain. If that is followed by a dry hot period there is a good chance your delicate seeds will dry out and perish.

Watering New Grass Seed

Newly germinated grass seed must be bedded on moist soil. I recommend watering new grass seeds with an oscillating sprinkler to avoid disturbing or moving the seed during germination. I recommend watering twice a day for three weeks during dry hot periods. If you have rainfall, then just treat this as a watering you can leave to nature, but pick up the rest of the watering schedule outside of this and keep the soil damp.

Once germination happens reduce watering to once per day for a further week or two until the grass roots take hold.

Sow Seeds at The Optimum Temperature

Following my advice on the optimum temperature for germination will also help speed up germination. If you broadcast sees and leave them sitting on cold soil, they will be inactive until the correct air and soil temperatures are achieved.

Pre Germinating Seeds

Pre-germinating seeds is a great way to kick-start the germination process. However, you cannot necessarily treat grass seeds in the same way as you would a plant or vegetable seed. By soaking seeds in water for 24 hours you can kick-start the process and get the seed husk fully soaked making the seed active.

However, grass seeds need to be broadcast and this is best done when the seed husk is dry. My advice is to follow the steps I have set out in soil preparation and watering as a priority, and the seeds will germinate in good time.

How Fast Does Grass Grow

Once the germination stage is complete grass growth happens in two areas, root development, and top growth or foliage. Our interest will be primarily focused on top growth.

On average grass grows 2 cm (0,8 inches) per week during the most active stage of growth. However, this is just an average, as it can grow much faster in some situations. So let’s look at what affects the growth rate of grass in more detail.

Grass Type Influences Growth Rate

The species of grass, as well as the type of grass (warm season vs cool season), will significantly influence the rate of growth throughout the year. The chart below offers a visual comparison of the rate of growth between warm and cool-season grass.

image
Reference: UC IPM

Cool-Season Grass

Cool-season grasses grow best during cooler temperatures, usually in the fall and spring. These grasses do well in cooler areas of the United States, such as the northeastern areas. Cool-season grasses include:

  • Kentucky bluegrass
  • Perennial ryegrass
  • Tall fescue
  • Bentgrass
  • Red Fescue

Warm-Season Grass

Warm-season grasses will germinate and grow best during the time of year when the temperatures are warmer, such as late spring and into the summer. They also grow well in warm climates, such as the southern areas of the United States. Warm-season grasses include:

Choosing the right grass for your region will help your lawn get off to a great start so it can grow and thrive. 

Conditions Affecting Grass Growth Rate

Aside from the species of grass, the environmental conditions have a significant impact on how fast grass will grow. Light, temperature, moisture, and soil condition all play their part in determining how well a species of grass can reach its potential.

Hours of Sunlight

Most species of grass require a minimum of 4-6 hours of sunlight each day. Without this, the grass’s growth will be limited and the lawn left prone to disease and pests. Therefore it stands to reason that a lawn receiving a full 12 hours of direct sunlight per day will grow faster than a lawn receiving 6 hours of light a day.

Temperature

Air and soil temperate will influence the rate grass will grow. As we have discussed earlier there is no single rule to the perfect temperature for grass, as it is different depending on the grass type (warm or cool-season grass)

Rainfall

We will all be familiar with a garden that has had no rain suffers, plants, trees, fruits, and of course grass. Periodic heavy rainfall if perfect for lawns. They prefer a deep soaking for the top 2-inches of soil, then clear skies to take in the maximum sunlight possible. So frequent rain can mean cloudy skies and limited sunlight, slowing down grass growth.

Soil Structure

Rich, loamy well-draining soil is ideal for most grasses. This will help with moisture retention and hold a good amount of nutrients for root and top growth development.

If the soil is too sandy it can become low in nutrients and dry out too fast to support optimum growth.

Soil pH

Most grasses grow best when the soil pH is between 6.0-7.0. If the soil is outside of this pH range it can mean the available nutrients in the soil are not absorbed by the plant’s roots. Leading to Chloris or mineral deficiencies.

You can check soil pH will a pH soil test kit and amend the soil with sulfur or lime to find the best pH for your lawn.

Soil Nutrients

There are three nutrients required to enable the fast growth of grass. Nitrogen (N), Phosphorus (P), and Potassium (K). Without a good balance of these nutrients, grass will suffer. For healthy and fast growth grasses prefer an N-P-K ratio of 15-0-5, 16-4-8, or similar. This is where Nitrogen is high for aggressive foliage growth, and Potassium is moderate for strong root development.

Fastest Growing Grass Type

Bermuda grass is the fastest growing grass species for lawns if you are located in a warm region such as the US. It germinates in 5-10 days and has a very fast growth rate in warm conditions.

It is also a drought-tolerant grass capable of lasting up to 3 months of dry weather. So on balance, it is arguably considered the fastest growing grass for lawn across a full growing season as it resists most environmental challenges and thrives.

How Fast Does Grass Grow on Average

Let’s do the math to estimate the average growth rate from seed to a blade of grass reaching 2″ tall

  • A germination rate of between 5-22 days
  • A growth rate of 1-3 cm per week

So we can take an average based on our sample of grass varieties identified at the beginning o this article to simulate an average growth rate from seed germination to a 2″ tall blade of grass

So, an average of 12 days of germination and 2 cm (0,8 inches) of growth per week give us an average estimate of 31 days on average to grow 2 inches (4.8cm) from seed.

However, in optimum conditions, the story is different. Grass seeds can germinate within 2-4 days, and then grow approximately 3cm per week (1,2 inches) in ideal conditions. So it is possible to grow grass from seed to 2″ tall in around 12 days.

Best Time to Plant Grass Seeds

Although you can scatter seeds at any point during the growing season, you will get the best results if you align your seeding with the natural cycle of growth. Different varieties of grass will grow better at different times of the year, so be sure you get the right kind for your climate and planting season.

There are cool-season grasses and warm-season grasses.

Cool Season Grass Seed

Fall is the best time to grow cool-season grass seeds. This is because the soil is still warm from the summer and the daytime temperatures are moderate, but not too hot. Cool evenings help keep the soil from getting too warm during the day. This balance of temperatures creates the ideal conditions for cool-season grass seed to germinate.

Soil temperatures should be between 50°F and 65°F when you sow your grass seed. You will want to plant any cool-season seed a minimum of 45 days before the first frost for your growing zone so the grass has time to get established before the frost hits. Fall precipitation means you will need to water less and the seed will be less likely to dry out.

Spring is also a good time to plant cool-season grass seed, however, the soil temperatures may not be quite warm enough for grass seed to germinate. You will need to make sure the soil temperature and air temperature are just right for success.

A wet spring can also give weeds a big advantage over young grass. If warm temperatures set in too quickly, it could stress new grass causing deterioration and leading to failure.

Warm Season Grass Seed

Warm-season grass seed germinates once the daytime temperatures are around 80°F and the soil temperatures are between 65°F and 70°F. The planting dates for warm-season grass will depend on your growing zone

Avoid planting warm-season grass seeds until all risk of frost has passed or your tiny grass seedlings may suffer from freeze burn and die. If the overall soil temperature is too cool or too wet for this type of seed, it will most likely rot.

Warm-season grass needs to be planted at least 90 days before the first frost date in your growing zone. This type of grass will go dormant when temperatures drop down into the fifties, so the seedlings need plenty of time to get established before the cool weather sets in.

Good timing will help the seedlings germinate and thrive before the fall weather hits.

It is possible to overseed warm-season turf with cool-season grass to add some green for the winter. This should be done in early fall and will extend the seasonal life of your lawn.

New Lawn Care

Once you’ve successfully germinated and grown your new lawn, it’ll need regular care and maintenance. There are a number of basic measures you can take to give yourself the best chance of enjoying a green and vibrant lawn.

Regular Watering

Too little or too much water is the leading cause of new-lawn failure. Be sure to plan ahead so you can water your new lawn appropriately. You’ll need to keep the soil moist when your grass seeds are germinating, but once the seedlings reach 2 inches in height, you can reduce the watering frequency.

Avoid Foot Traffic

Try not to play on or walk on new lawns for the first three weeks of growth.

Do Not Mow Too Soon

Wait to mow your lawn until it is 3 to 4 inches tall. The first time you mow your new lawn, just cut it slightly to make it look neat but be very careful not to pull out the tender seedlings.

The next time you mow, you can cut the lawn to the maximum height recommended for your type of grass. Never remove more than 30% of its height at a time.

Fertilizing New Lawn

Don’t fertilize your new lawn for at least the first six weeks of growth. If your soil is in good condition you may not need to apply any at all. If you are unsure, wait and apply fall fertilizer.

FAQs How Long Does It Take Grass Seed To Grow

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