How to sow grass seed: when to sow, preparing the ground and caring for a new lawn

A lawn from seed costs much less than turf, but it takes patience and good preparation. Sow in early autumn or mid-spring, prepare a fine, firm seedbed, spread the seed evenly and keep it moist — that covers most of what decides success.

To work out how much seed to buy, measure your lawn with our lawn area calculator, then multiply by the sowing rate on the packet.

When to sow grass seed

The Royal Horticultural Society (RHS) recommends autumn (September–November) or mid-spring (March–April). If you have a choice, early autumn is better: the soil is still warm, rain is more reliable and the seedlings can establish before the first hard frosts. Spring-sown grass tends to root in more slowly.

Avoid sowing in hot, dry summer weather unless you can water every day.

Choosing the right grass seed

The RHS describes three main types of mix:

Mix	Typical grasses	Best for
General-purpose / hard-wearing	Perennial ryegrass, tall fescue, red fescues, browntop	Family lawns, children and pets. Grows quickly and needs regular mowing.
Luxury / fine	Chewings fescue, creeping red fescues, browntop	Ornamental lawns that can be mown short. Slow-growing, less hard-wearing.
Shady	Hard fescue, creeping red fescues, browntop	Light to medium shade. Usually not very hard-wearing.

“Drought-tolerant”, “quick” or “easy-care” mixes are usually a variation on one of these. Buy good-quality seed: the RHS warns that cheap seed may contain weeds or coarse agricultural ryegrass. Any ryegrass listed should be a turf or fine ryegrass.

Preparing the ground

Start several weeks before you want to sow.

1. Clear perennial weeds such as couch grass and bindweed, digging out the roots.
2. Dig or rotovate compacted soil to about 20 cm deep. Add well-rotted manure or compost to light, sandy soil.
3. Let the soil settle — ideally for five to six weeks — and hoe off any weed seedlings that appear.
4. Firm the ground by treading over it with small, shuffling steps in several directions.
5. Rake it level, removing stones and breaking up lumps until you have a fine, crumbly surface.
6. If you like, rake in a general-purpose fertiliser. The RHS suggests about 70 g per m².

How to sow grass seed

1. Weigh the seed for your area using the rate on the packet — rates vary between mixes.
2. Split it into two equal batches.
3. Sow the first half walking up and down the lawn in parallel rows, and the second half walking from side to side. This gives an even cover without bare stripes.
4. Rake lightly so most of the seed is just covered with soil.
5. If no rain is forecast, water gently with a fine spray so the seed is not washed away.
6. Birds love grass seed. Horticultural fleece weighted at the edges protects the seed and can help germination. Where birds are a big problem, the RHS suggests increasing the sowing rate by 50%.

The seedlings should appear seven to ten days after sowing in good conditions.

Looking after a new lawn

• Water every few days if it does not rain, using a can with a rose or a gentle hose spray.
• When the grass is 5–7.5 cm tall, lightly firm the soil with a roller or the back roller of a mower. Two or three days later, give the first cut, taking off no more than a third of the height with sharp blades.
• Autumn-sown lawns usually need no more mowing until spring. Spring-sown lawns can be mown every week or so, lowering the blades gradually.
• Keep off it as much as possible for about eight months. An autumn-sown lawn should not be used much before June.

Common mistakes

• Sowing into ground that has not been weeded or allowed to settle
• Leaving footprints and bumps that become dips once the grass grows
• Sowing too much seed, or too little
• Letting the surface dry out during germination
• Mowing too early or too short

Quick checklist

• Lawn area measured and seed weighed
• Mix chosen for wear and shade
• Weeds cleared, soil dug, settled, firmed and raked
• Seed sown in two directions and lightly raked in
• Bird protection and watering in place