How to Apply Lawn Seed
To apply lawn seed, prepare a firm, level seedbed, spread the seed evenly at roughly 35g per square metre for a new lawn or 25g for overseeding, then lightly rake it in, water gently and keep the surface moist until it germinates. Spring and early autumn are the easiest windows; you can sow in summer too, but only if you can water every day.
Getting grass seed to grow is rarely about the seed itself, it is about how you apply it. Do the prep, spread it evenly at the right rate and keep it watered, and you will get a thick, even result whether you are sowing a brand-new lawn from scratch or overseeding tired, thin grass. Here is the method, step by step.
How do you apply lawn seed?
Start with the seedbed, because seed only germinates well where it makes good contact with soil. For a new lawn, clear and level the ground, then rake it to a fine, crumbly tilth. For overseeding an existing lawn, mow short, scarify or rake hard to pull out moss and thatch, and loosen the surface so seed can reach soil rather than sitting on top of dead grass. Once the surface is open and firm, spread the seed evenly, by hand for small areas or with a spreader for larger ones. The trick to even coverage is to sow in two passes at right angles to each other, half the seed in each direction, so you never end up with thick stripes and bare gaps.
What seed rate should you use per square metre?
Rate matters more than people think. Too little and the lawn comes through thin and patchy; too much and the seedlings crowd and compete, which weakens them and invites disease. As a practical guide, sow a new lawn at around 35g per square metre, and overseed an existing lawn at roughly 25g per square metre, since you are only filling gaps in grass that is already there. Weigh out the seed for the area rather than guessing, and always check the rate on your seed pack, as it varies by mix.
Do you rake in seed or cover it?
Lightly rake the seed in so most of it sits just below the surface, or top new ground with a thin scatter of topdressing no more than about 5 to 10mm deep. The aim is good seed-to-soil contact, not burial: seed sown too deep simply will not come up. A light topdress also holds moisture around the seed and hides it from hungry birds while it gets going.
Working a high-phosphorus pre-seed feed into the seedbed before you sow gives the new grass the nutrients it needs to drive roots down quickly, which is exactly what young seedlings are racing to do in those first vulnerable weeks.
How do you water and look after new grass seed?
Watering is where most sowings are won or lost. Once the seed is down, water gently with a fine spray so you wet the surface without washing the seed into clumps, then keep that top layer of soil consistently moist, never letting it dry out and never leaving it waterlogged. In warm weather that usually means a light water once or twice a day until the seedlings establish, which takes around one to three weeks depending on the mix and the temperature. Keep off the area while it is establishing, hold back the weed killers, and leave the first cut until the new grass reaches about 5 to 7cm, then take only the top third off with a sharp mower.
When is the best time to apply lawn seed?
Grass seed needs warm soil and steady moisture, so the two easiest windows in the UK are spring and early autumn. Early autumn is often the pick of the two: the soil is still warm from summer, the air is cooler and the rain does much of your watering for you. Spring works well once the soil has warmed up. Right now, in the middle of summer, sowing is harder, hot, dry soil and thirsty seedlings mean watering every single day, and a missed day in a heatwave can lose the lot. You can still sow in summer if you are set up to water religiously, but if the job is not urgent it is often worth waiting for early autumn. For more on the summer trade-off, see our guide on when to sow grass seed in summer.
MyLawn is Mowd's free lawn-care app. It looks at your postcode's weather, the season and your lawn, then tells you the single best thing to do next, in plain English, with reminders so watering and feeding never get forgotten. If it is a bad week to seed, it will say so and nudge you when conditions turn. Take a look at MyLawn.
Related Mowd guides: How and Why to Scarify Your Lawn · Lawn Renovation: A Step-by-Step Guide · UK Lawn Feeding Calendar
Frequently asked questions
How much grass seed do I need per square metre?
- Around 35g per square metre for a new lawn and about 25g per square metre for overseeding existing grass, where you are only filling gaps. Always check your seed pack, as the rate varies by mix, and weigh it out for the area rather than guessing.
Do I need to rake grass seed in or cover it?
- Lightly rake it in or top with a thin layer of soil up to about 5 to 10mm deep, so the seed makes good contact with soil and is hidden from birds. Don't bury it, as seed sown too deep will not germinate.
How long does grass seed take to germinate?
- Usually one to three weeks, depending on the seed mix and soil temperature. Warm soil speeds it up, but the seedbed must stay consistently moist, missing watering in warm weather is the most common reason sowing fails.
What is the best time of year to sow grass seed in the UK?
- Spring and early autumn, when the soil is warm and moisture is reliable. Early autumn is often easiest because the rain does much of the watering for you. You can sow in summer, but only if you can water every day and avoid heatwaves.