Almost always moisture or contact. Cold soil is third, and the seed itself is a distant fifth.
1. It dried out after swelling
The irreversible one. Seed takes up water and begins to germinate; if the surface then dries before the root establishes, the seed is dead rather than dormant. One hot, windy afternoon does it.
This is why the watering after sowing has to be light and frequent rather than heavy and occasional — the top centimetre is what matters, and it dries fastest.
2. It never touched soil
Seed sown onto thatch, onto a crust, or onto an unraked surface sits above the ground and germinates into air. Raking in, or a thin covering of a topsoil or sand mix, is what puts the seed where it can work.
On an overseeded lawn this is the argument for scarifying first: the openings the blades leave are the seedbed.
3. The soil was too cold
Air temperature misleads. Soil lags it by weeks in spring, and seed sown into cold ground sits there — sometimes for a month, sometimes until it rots.
4. It was washed or eaten
Heavy rain on a slope moves seed to the bottom of it, which shows as a bare top and a dense line at the base. Birds take what is lying loose on the surface.
5. The seed itself
Last on the list because it is rarely the answer. Old seed stored damp loses viability, and there is no way to judge a bag by looking at it. If everything else was right and nothing came up anywhere, this is what is left.
What to do now
Wait longer than you want to — three to four weeks on a mixture, because species germinate at different rates. Then reseed the areas that are genuinely bare, rake in properly, and keep the surface damp.
How this site handles it
The seed and lawn soil shelves here print coverage rates and what the maker says the product is for. Where a product is a seed-and-soil mix or a seed-and-feed combination, the page says so, because those have different rates and different instructions from plain seed.
The questions that keep coming in
How long should I wait before deciding it failed?
Longer than feels reasonable. Different species in a mixture germinate at very different speeds, and a stand that looks patchy after ten days often evens out over the following three weeks.
Do birds really take that much?
They take some, and they are visible, which is why they get blamed for failures that were dryness. Seed raked in or lightly covered is largely out of reach; seed left on the surface is a meal.
Last reviewed 26 September 2026