How Much Grass Seed Do I Need Per m²? UK Lawn Guide

A new lawn needs about 35 grams of seed per square metre. A 6 × 5 m lawn takes 1.2 kg with 10% extra, which is two 1 kg boxes. Overseeding an old lawn needs about 20 g per m². Early autumn, from September to October, is the best time to sow in the UK.

Seed by lawn size

With 10% extra for uneven spreading, and the rolls of turf for the same lawn to compare:

Use the lawn seed calculator for a shady or hard-wearing mix (50 g per m²) or for patching (15 g per m²). The rate on your pack comes first.

Seed or turf?

• Seed is cheaper, often a tenth of the cost of turf, and you can choose the mix to suit the shade, the wear and the soil.
• Turf is faster: you can use the lawn within a few weeks, while a seeded lawn takes a couple of months to be ready for play.
• Seed takes more care: it needs even watering, protection from birds and a weed-free bed, and it is at risk from heavy rain washing it away.
• The ground prep is the same. Whichever you choose, the preparation decides how good the lawn will be.

How to sow it

1. Clear weeds and stones, dig over the soil, break up the lumps, and level it. Tread it firm.
2. Rake in a pre-seeding fertiliser a few days before you sow, then rake to a fine, level tilth.
3. Weigh out the seed for the area, or measure it with a scoop, and divide it into two halves.
4. Sow one half in one direction, the other at right angles, then rake it in very lightly.
5. Water gently every day or two if it is dry. Keep off it until the grass is about 6 to 8 cm tall, then mow with the blades high.

Choosing the right mix

A hard-wearing mix suits a family lawn and has perennial ryegrass in it. A shade mix suits the ground under trees, though no grass likes deep shade. A fine ornamental mix gives a lawn that looks good but wears badly. If you only need to patch bare spots, buy a small box of a quick-growing repair mix.

Mistakes that cost people money

• Sowing too thinly, which leaves gaps that fill with weeds, or too thickly, which lets the seedlings choke and rot.
• Letting the seedbed dry out in the first few weeks.
• Sowing in the middle of summer, or in a cold winter.
• Mowing too early, or too short.

Frequently asked questions