Roughly double for a new lawn what you use for overseeding — and the bag states one of the two. Read which one before buying by area.
The two rates
A new lawn, sown onto bare prepared soil, needs enough to produce a complete sward on its own. This is the higher rate, and it is the one most bags print.
Overseeding an existing lawn needs much less, because the established grass is already occupying most of the ground. Here the seed is filling gaps, not building a sward, and the rate is typically about half.
Using the new-lawn rate to overseed wastes seed and produces a crowded, competing stand in the patches that do take.
Why heavier is not better
Grass seedlings compete for the same light, water and root space. Sown too thickly, they come up dense and etiolated, they thin themselves out over the following weeks, and what survives is weaker than a correctly sown stand would have been. Crowded seedlings are also more prone to damping-off in wet conditions.
The lawn’s density in its second year comes from tillering — established plants producing new shoots — not from how many seeds you put down.
Why bags are not comparable by mass
Seed count per gram varies substantially between mixtures. A hard-wearing mixture built around large ryegrass seed has far fewer seeds in a kilogram than a fine ornamental mixture does, so the same ground needs a different mass.
Compare the stated rate per square metre, which every reputable bag gives, rather than the bag size or the area claim on the front.
Spreading it evenly
By hand on a small patch, in two passes at right angles, each with half the seed. On anything larger, a spreader — and the setting for seed is not the setting for fertiliser, so a spreader used for both needs recalibrating each time.
How this site handles it
The seed pages here print the maker’s stated rate and the mixture description as given. The spreader shelf is a separate family, and those pages state the working width and whether the machine has a calibration setting, because a spreader without one is a machine you set by trial.
The questions that keep coming in
Is it worth sowing extra to be safe?
No. Seedlings that germinate too close compete with each other, and a crowded stand is weak and disease-prone. Seed that does not establish is money on the ground.
Why do the bags differ so much in stated coverage?
Because the mixtures differ. A fine ornamental mixture has far more seeds per gram than a hard-wearing one with large ryegrass seed, so the same coverage needs a different mass. Compare the rate, not the bag size.
Last reviewed 26 September 2026