How Long Does Grass Seed take to Grow?

You’ve sown your grass seed, watered it in, and now you’re watching the bare soil like a hawk. How long until you see green? And when will it actually look like a proper lawn?

The short answer: most grass seed germinates within 7-14 days. But the full picture depends on the type of seed, soil temperature, and how well you’ve prepared the ground.

Germination Times by Grass Type

Perennial Ryegrass: 5-14 days. The fastest germinator and the backbone of most UK lawn seed mixes. Ryegrass is quick to establish, hardwearing, and tolerates a wide range of conditions. If your seed mix is ryegrass-dominant, expect to see green shoots within a week or so.

Fescues (red fescue, tall fescue): 10-21 days. Slower than ryegrass but worth the wait. Fescues are more drought-tolerant, shade-tolerant, and create a finer-textured lawn. They need slightly warmer soil to get going.

Bent grass: 14-21 days. The slowest to germinate but produces the finest, most ornamental lawn. Bent grass needs warmer soil temperatures (around 15°C) and is typically found in premium lawn mixes.

Most lawn seed mixes contain a blend of these species, so you’ll see the ryegrass come up first, followed by the fescues, then the bent grass. Don’t panic if germination seems patchy in the first week – the slower species are still on their way.

The Critical Factor: Soil Temperature

Soil temperature matters more than air temperature. Seeds germinate in the soil, not the air, and soil warms up and cools down much more slowly than the air above it.

Minimum soil temperatures for germination:

• Perennial ryegrass: 7-8°C (will germinate, but slowly)
• Fescues: 10-14°C
• Bent grass: 15°C

For reliable, quick germination across all species in a typical lawn mix, aim for soil temperatures consistently above 10°C. In the UK, this usually means sowing from late March through to mid-October, with the best results in April-May or September.

A soil thermometer costs a few pounds and takes the guesswork out of timing. Push it into the soil at seed depth (about 1cm) and check in the morning when soil is coolest.

Week-by-Week: What to Expect

Days 1-7: Nothing visible. Seeds are absorbing moisture and beginning to germinate below the surface. Keep the soil consistently moist – this is the most critical period. If seeds dry out now, they die.

Days 7-14: First green shoots appear, starting with the ryegrass. The lawn will look sparse and patchy – this is normal. Continue watering regularly.

Days 14-21: More grass emerges as the slower-germinating fescues catch up. The green coverage becomes more even. Seedlings are still fragile – avoid walking on the area.

Weeks 3-4: Grass thickens up noticeably. Roots are establishing. You can reduce watering frequency slightly but don’t let it dry out completely.

Weeks 4-6: Lawn approaches first-mow height (7-10cm). Root system is developing but still shallow. Continue to treat it gently.

Weeks 6-8: Lawn is established enough to mow regularly and handle light foot traffic. Roots are deeper and more resilient.

How to Speed Up Germination

You can’t rush nature, but you can give your seeds the best possible conditions:

Prepare the soil properly. Loose, fine soil allows seeds to make good contact with the ground and roots to penetrate easily. Dig over the area, break up lumps, rake to a fine tilth, and firm gently before sowing.

Sow at the right depth. Grass seed needs light to germinate. Cover with no more than 5mm of soil – or simply rake the seed in lightly. Seeds buried too deep won’t germinate at all.

Water consistently. The top 3-4cm of soil should stay moist (not waterlogged) throughout germination. Water lightly once or twice daily in dry weather, using a fine spray to avoid displacing seeds.

Choose the right time. Sowing when soil is warm and moisture is reliable (spring or early autumn) gives faster results than sowing in cold or dry conditions.

Use fast-germinating varieties. Seed mixes with a high proportion of perennial ryegrass germinate faster than fine fescue or bent grass mixes.

Why Isn’t My Grass Seed Growing?

If it’s been three weeks and nothing’s happening, something’s wrong. The most common causes:

Seeds dried out. The number one killer. Once germination starts, seeds need constant moisture. Even a few hours of drying out can kill them. Check your watering routine.

Soil too cold. If you sowed too early in spring or too late in autumn, seeds may be sitting dormant waiting for warmth. They might still germinate when conditions improve – or they might rot. Check soil temperature.

Seeds buried too deep. If you covered the seed with more than 1cm of soil, it may not have enough energy to reach the surface. Grass seed needs to be barely covered.

Poor seed-to-soil contact. Seeds sitting on top of lumpy, unraked soil can’t absorb moisture properly. Preparation matters.

Old or poor-quality seed. Grass seed has a limited shelf life. Old seed has lower germination rates. Always buy fresh seed from a reputable supplier.

Birds ate it. If you didn’t lightly rake seed in or cover it, birds may have had a feast. Some bare patches among growing grass suggest bird damage.

When Can I Walk on New Grass?

Before germination, light foot traffic (for watering, checking progress) is fine – you’re walking on soil, not seedlings.

Once seedlings emerge, avoid walking on them as much as possible. Young grass is fragile and easily damaged. The roots are shallow and can be pulled out or crushed.

After the first mow or two (around 6-8 weeks), you can start using the lawn normally. The grass is established enough to handle foot traffic, though it’s still best to avoid heavy use until the end of the first growing season.

When Can I Mow New Grass?

Wait until the grass is at least 7-10cm (3-4 inches) tall before the first cut. This usually takes 4-6 weeks from germination, depending on growing conditions.

For the first mow:

• Set your mower to its highest setting and take off no more than one-third of the grass height. So if the grass is 9cm tall, cut it to 6cm. Cutting too short stresses the young plants and weakens the root system.
• Use a sharp blade. Blunt mower blades tear grass rather than cutting it cleanly, which damages young plants and invites disease.
• Mow when the grass is dry. Wet grass clogs mowers and can be pulled out rather than cut.

After the first few mows, you can gradually lower the cutting height over several weeks until you reach your preferred lawn height (usually 3-4cm for most UK lawns).

Frequently Asked Questions

How long does grass seed take to germinate?

Most grass seed germinates within 7-14 days, but it varies by species. Perennial ryegrass is fastest (5-14 days), fescues take 10-21 days, and bent grass needs 14-21 days. Soil temperature affects speed – warmer soil means faster germination.

Why isn’t my grass seed growing?

The most common reasons are: seeds drying out during germination, soil too cold (below 7-10°C), seeds buried too deep (should be barely covered), poor seed-to-soil contact, old seed, or bird damage. Check your watering first – dried-out seeds are the most common cause of failure.

When can I walk on new grass?

Avoid walking on new grass until after the first mow (around 6-8 weeks). Young seedlings are fragile and easily damaged. Light foot traffic for watering is fine, but don’t use the lawn properly until it’s established.

When should I first mow new grass?

When the grass reaches 7-10cm (3-4 inches) tall, usually 4-6 weeks after germination. Set your mower to its highest setting and remove no more than one-third of the height. Use a sharp blade and mow when dry.

What’s the fastest growing grass seed?

Perennial ryegrass is the fastest-germinating grass, showing green shoots in as little as 5-7 days under good conditions. Seed mixes with a high proportion of ryegrass will establish quickest. Fine fescues and bent grass are slower but produce a finer-textured lawn.

The Bottom Line

Grass seed typically takes 7-14 days to germinate and 6-8 weeks to establish into a usable lawn. The keys to success are soil temperature (above 10°C), consistent moisture, proper preparation, and patience.

If you’re watching bare soil and nothing’s happening after two weeks, check your watering routine first. Dried-out seeds are the most common reason for failure. And if you’re sowing in marginal conditions (early spring or late autumn), expect things to take longer.

For more seeding guides and lawn care advice, browse our lawn care guide library.