How Long Does Grass Seed Take to Grow? And How to Speed Up Germination

by Daniel Hunter

On average, grass seed germinates within 5-10 days. Within 6-10 weeks, you’ll have a well-established lawn you and your family can use.

That said, it could take longer, or it might not take as long. The length of time your grass seed takes to germinate and grow depends on 4 factors.

If you want to get your lawn from seed to a full, useable lawn you need to understand how these factors affect growth.

And if you don’t like waiting, I’ll show you two ways to speed up grass seed germination.

So let’s get into it.

4 Factors That Affect How Long Grass Seed Takes to Grow

There are 4 factors that affect how long grass seed takes to germinate. Provided you’ve sown it right, obviously!

They are;

  • Grass species
  • Time of year
  • The weather
  • Aftercare

Let’s look at each one individually.

Grass Type or Species

Temperatures for grass seed germination

Different types and species of grass germinate in different soil temperatures.

In the graph above, you can see that;

  • Ryegrasses: (Found in most hard-wearing, utility and family lawn seed blends) germinates in soil temps as low as 8 degrees Celsius.
  • Red Fescue: (Found in many family, utility and formal lawn seed mixes) needs warmer soil temperatures of at least 12 degrees Celcius
  • Bentgrasses: (Found in ornamental seed mixes) needs the soil temperature to be at least 15 degrees Celsius.

Most grass seed blends often contain a mixture of grass types. For example, many family lawn seed blends contain a mixture of ryegrass and fescues.

If you sow a seed mixture like this early in the season, you can expect the ryegrass to germinate and grow first. Your lawn might look a little sparse until the soil temps are warm enough for the fescues to germinate. This is normal.

Formal lawn seed often contains fescues and bentgrasses. As they need warmer temperatures, you’re better off sowing a little later in the season. If it’s too cold, the seed won’t germinate.

Weather Conditions

Sunshine, water and warmth are the fuel that power germination and growth. That means you should lay grass seed in the seasons that provide all these conditions.

And the best seasons for sowing grass seed, my fellow lawnsmith, are spring and autumn.

Now, spring and autumn might be the best seasons (based on historical data). But that doesn’t mean they provide the best weather conditions.

I mean, let’s face it, the UK weather is pretty unpredictable. Oftentimes, even the weather itself doesn’t know what it’s doing so we have no hope!

For example, some Aprils provide perfect conditions. They’re warm, bright and provide plenty of rain. Others (like 2021), are cold and frosty.

All you can do is check your local two-week weather forecast. Then pick a window that provides the best conditions.

Regardless of whether it’s April, May or June, f it’s too cold, wait. If it’s warm, go ahead. If it’s dry, you’ll need to water it yourself.

The Soil Conditions

For fast germination and growth, the seedbed (or soil) needs to be in good condition.

It should be;

  • Firm but not compacted
  • Free of moss, weeds and other debris like rocks and roots
  • Able to hold onto water without waterlogging
  • Contain enough nutrients to support germination and growth

If you’re sowing seed for a new lawn, you can make all these adjustments while you’re preparing the ground. Dead easy to do!

After that, the soil needs to be warm enough and moist enough to help germination and growth. Depending on when you sowed your grass seed, germination may be quick, it might be slow. If you did it earlier in the season and the soil is cold, it’ll take longer. Also, if there’s no rain, you’ll need to help things along with regular watering.

Proper Aftercare

So you’ve;

  • Prepared the ground to create a good seedbed
  • Sown the seed using the best grass seed for your garden, soil and use, and
  • Done it when the weather is on your side (or as much as it can be)

The only thing you need to do now is to make sure it gets enough water.

That said, watering new grass seed is an act of balance.

See, you need to keep the seed damp but not soaking wet. So water it in the morning and evening for about 5 minutes. If it’s warm, water in the middle of the day too.

Don’t water if it’s raining though as the ground will become too wet.

Once the seed has germinated, increase the watering time to 10 minutes. This will mean the water gets a little deeper into the soil and encourage the new grass roots to grow downwards.

How to Speed Up Grass Seed Germination

cover grass seed with clear plastic sheeting to speed up germination

Waiting for grass seed to germinate can feel like it takes forever. Especially if conditions aren’t ideal.

If only there was a way to speed it up!

Well, my fellow lawn lover, there is.

Get some clear, heavy-duty plastic sheeting (like this one on Amazon) and cover your lawn with it. When the sun shines, it’ll let the light through and trap the heat within it to create a greenhouse effect. This will raise the soil temperature pretty quick.

I like to raise the sheeting off the lawn by 6 inches or so there’s plenty of air to warm up. And it won’t flatten the grass as it grows.

One downside to using plastic sheeting is that it makes watering your grass seed a pain in the ass. You’ll have to remove the sheeting every time you need to water the area. This means if you’ve got massive lawns, it might not be worth doing.

That said, it’ll stop the birds from eating your grass seed!

To Sum Up

Getting grass seed to germinate isn’t difficult. That said, many people struggle with it.

But all you need to do is;

Do these right and your grass seed will grow in no time.

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