Growing a lawn from seed

Most gardens have a patch of grass somewhere. Many people start a new lawn, or mend a tired one, by sowing seed.

When to sow

The Royal Horticultural Society (RHS), the UK's gardening charity, suggests sowing in autumn, from September to November, or in mid-spring, in March and April. Lawn seed comes up best in early autumn and mid-spring. The soil is warm and moist then, and the weather is mild.

If you can choose, the RHS prefers early autumn. Seedlings sown then can settle before the first hard frosts, and they root in well through the winter. Grass sown in spring may root in more slowly, because it puts its energy into flowering. The Met Office also points out that April can still bring a damaging frost.

Choosing a seed mix

Lawn seed is sold as a mix of grasses. The RHS describes three main kinds.

A general-purpose mix has hard-wearing grasses that stand up to children, pets and regular footsteps. It grows quite fast and needs regular mowing.
A fine lawn mix has fine-leaved grasses that make a dense, soft lawn. You can mow it low for a neat finish, but it takes less wear.
A shady lawn mix suits light to medium shade, such as under trees or beside a fence or hedge.

The RHS advises reading the ingredients on the packet. Any perennial ryegrass in the mix should be listed as a "turf" or "fine" ryegrass.

Preparing the ground

The RHS suggests getting the ground ready several weeks before sowing. Dig out the roots of perennial weeds such as couch grass and bindweed. If the soil is hard and compacted, dig it over to a depth of about 20cm. Leave it to settle, ideally for five to six weeks.

Then firm the soil by treading over it in small, shuffling steps. Rake it in different directions until the surface is level, fine and crumbly.

Sowing the seed

The packet gives the weight of seed to use for each square metre. The RHS suggests splitting the seed into two equal batches. Scatter the first half walking up and down the area, and the second half walking from side to side. Then rake lightly to cover most of the seed.

Horticultural fleece, weighted down at the edges, keeps birds off and holds warmth and moisture in the soil. If no rain is forecast for a few days, water gently with a fine spray.

Looking after new grass

Grass seedlings usually appear a week to ten days after sowing. Water them regularly in dry weather with a gentle spray. When the grass is between 5cm and 7.5cm tall, firm the soil lightly. Two or three days later, give it a first cut that takes off only about a third of its height.

The RHS suggests using a new lawn as little as possible for about eight months. For an autumn sowing, that means keeping off it until around June.

Mending bare patches

The RHS calls spring and autumn the ideal times to repair a lawn, when the weather is cool and damp. To reseed a bare patch, cut out the damaged turf, fork over the soil and work in some compost or topsoil. Sow at the rate on the packet, usually about 15g to 25g of seed per square metre. If shade caused the patch, the RHS advises a seed mix made for shady places.

In a dry summer an established lawn may turn brown. The RHS advises leaving it unwatered, because the grass sends up new leaves once the rain returns. A newly sown lawn does need water in dry spells, and the RHS suggests stored rainwater or grey water in place of mains water.