Grass seed is sown at a rate in grams per square metre, and sold by the box or bag in kilograms. The rate depends on the seed and the job, so it is the number to read off the box.
Starting rates
Baglist starts at 30 g per square metre for a new lawn and 15 g for overseeding an existing one. These are starting points to check against the box, not a recommendation for a variety.
Some boxes print a different figure. A Munns kikuyu bag in Australia prints its own coverage, which is not the same as a general lawn mix.
| Area | New lawn, 30 g/m² | Overseeding, 15 g/m² |
|---|---|---|
| 10 m² | 0.3 kg | 0.15 kg |
| 25 m² | 0.75 kg | 0.375 kg |
| 40 m² | 1.2 kg | 0.6 kg |
| 100 m² | 3 kg | 1.5 kg |
A worked lawn
A 40 m² new lawn at 30 g/m² needs 1200 g of seed. Bunnings lists Garden Basics lawn seed in 1 kg bags, so that is two bags. Overseeding the same lawn at 15 g/m² is 600 g, one bag.
Sowing evenly
Half the seed sown one way and half at right angles gives a more even cover than one pass. Seed left over keeps for patching if it is stored dry.
The count does not include topsoil or a top dressing. The Topsoil calculator gives the volume for a layer over the area.
Figures are estimates for a shopping list. Check the pack or datasheet before you buy.