If your grass seed has not come up, check the soil at seed depth before adding more. Cold soil, a drying surface and poor contact with the ground can all delay establishment. Seed that has washed into hollows may also leave bare strips beside thick patches of shoots.
A few quiet days do not mean the seed has failed. Look for a sustained spell of suitable conditions, and compare the bare areas with the parts that are growing.
If fresh seed is needed, I recommend Hurrells Seeds. Choose the mixture for the lawn you want to maintain; the grass seed buying guide explains the main options.
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Has the seed had enough time in suitable conditions?
Count the days since sowing alongside the weather, rather than using the calendar alone. A week of cold, saturated ground tells you far less about the seed than a week of mild weather with evenly moist soil.
The Grounds Management Association gives roughly seven to fourteen days for perennial ryegrass under good conditions. A mixture containing slower grasses will not necessarily emerge evenly. Look at the species on the bag before deciding that the first green shoots should already have filled the whole area. See the guide to grass seed mixtures for why those ingredients matter.
A soil thermometer is useful when sunny afternoons make the garden feel warmer than the ground. Take readings in representative parts of the seedbed, including the colder shaded area, and compare them with the seed supplier’s guidance. One warm reading in the afternoon does not describe the whole day.
For choosing a better sowing window, use the UK grass seed sowing guide. The GMA establishment guidance also explains the conditions that slow germination.
Check moisture where the seed is sitting
Part a small area of the surface with your fingers. Is the soil immediately around the seed moist, powdery or saturated? A damp layer farther down is little help to seed sitting dry on top, while shiny puddles can hide ground that is short of air.
Check more than one spot. The edge beside paving, the middle of the lawn and the strip under a tree may need different attention. Water from a sprinkler does not always reach all three equally, especially in wind.
Before germination, a dry seed may simply be waiting for water. Once a root has emerged, the seedling is much more vulnerable to drying. You cannot reliably tell which seeds have survived by looking across the lawn, so restore gentle, even moisture and watch the response before scattering another full application.
Use a fine spray that leaves the seed in place. Adjust watering to the surface and the weather, following the new grass seed watering guide. Avoid treating a freshly sown area like an established lawn with deep roots.
Is the seed touching soil, or caught above it?
Seed caught in old grass clippings or a thick thatch layer can dry out between waterings. Walk around the edge of the work and look closely: some seed should be in contact with the prepared surface, rather than balanced on a mat of dead material.
The opposite problem is burying it beneath a heavy layer of soil or compost. Small grass seedlings have limited reserves. Follow the mixture’s sowing instructions and keep any covering light; a deep topdressing applied after sowing can leave some seedlings struggling to reach daylight.
If shoots are already appearing, do not rake the whole area again to rescue a few bare spots. Protect the emerging grass and work only on the genuinely failed patches once the cause is clear. The RHS seed-sowing guide describes preparing a firm, fine surface and lightly covering the seed.
Use the pattern of growth to narrow down the problem
| What you can see | What to check next |
|---|---|
| Almost nothing across the whole area | Soil temperature, moisture, seed storage and any recent lawn treatment |
| Good growth in shelter, little on an exposed edge | Drying wind, sprinkler coverage and differences in surface moisture |
| Dense seedlings in hollows or along a run-off line | Whether heavy rain or watering moved the seed |
| Stripes of seedlings with bare bands between | Missed sowing passes, uneven spreading or uneven preparation |
| Seedlings appeared, then collapsed or disappeared | Drying, waterlogging, disturbance or seedling disease rather than a simple delay |
Where growth is poor beneath a tree, check both shade and moisture. The soil may be drier because roots are taking up water, even though the surface is sheltered from the sun.
Photograph the same small areas every few days from the same position. Fine new shoots are easy to overlook when you inspect the entire lawn each morning. Avoid repeatedly lifting seed or digging through the bed to see what is happening.
Check the bag and recent lawn treatments
Seed stored somewhere hot or damp deserves closer attention, especially if a fresh bag sown alongside it is growing normally. Test a representative sample using the home grass seed germination test. That separates a possible seed-storage problem from conditions outdoors without sacrificing another lawn-sized application.
Keep the bag label, batch details and any spare seed. If emergence is poor despite suitable conditions, those details give the supplier something useful to investigate.
Also check what went onto the ground before sowing. Weedkillers and combined lawn treatments can have specific reseeding intervals. Read the exact product label; the waiting period for one treatment should not be applied to another.
Adding more fertiliser is not a reliable way to wake up seed. If a starter feed was already used, check its rate and instructions before adding anything else. Germinating grass initially draws on reserves within the seed, as explained in Penn State’s account of grass growth.
When should you wait, and when should you resow?
Wait when shoots are steadily increasing, the mixture includes slower species, or the ground has only recently become suitable. Keep the area protected while it develops. There is no useful universal deadline at which every unsprouted seed can be declared dead.
Resow when seed has clearly washed away, a storage test shows poor viability, or isolated areas remain empty after the rest has established under comparable conditions. First correct the problem: loosen a crusted surface, remove the mat preventing soil contact, or improve water coverage as appropriate.
Measure the failed area and use the rate stated for the job. The grass seed quantity guide helps with that calculation. Avoid tipping a second full dose over healthy seedlings just because the lawn is not yet dense.
If the soil has turned persistently cold or wet, prepare for the next suitable window instead. Once growth is underway, move on to new lawn aftercare for the first cuts and the change in watering as roots develop.
