Seeding bare patches and overseeding the whole lawn

Grass is one of the easiest plants on the planet to grow from seed — provided you get a few conditions right. The two seeding jobs every gardener deals with are patch repair (bare spots, dog damage, scuff marks) and overseeding (refreshing density across the whole lawn each autumn). Same bag of seed, slightly different methods.

Mowd stocks two lawn-seed mixes covering most domestic situations:

• Family First — fast-establishing, hard-wearing ryegrass-and-fescue blend for back lawns that take traffic from kids and pets. Maintained at ~20 mm.
• Envy — fine-textured fescue-led mix for showpiece front lawns and statement turf. Cuts down to ~13 mm.

Pick whichever matches the use of the lawn rather than mixing them on the same area — the two have different growth habits and target heights.

Why this matters

A lawn loses density over time. Foot traffic, kids, dogs, summer drought, the odd moss patch — they all leave thin spots that weeds love to colonise. Seeding closes those gaps before the gap-fillers move in.

Overseeding once a year — typically autumn — keeps a long-term lawn dense without needing major renovation. It's a small annual habit that compounds over years; a lawn overseeded for several seasons in a row looks markedly different from a lawn that's been left to fend for itself.

When to do it

• Patch repair — anytime soil temperatures are above 10 °C and you can keep the patch consistently moist for 2–3 weeks (typically Mar–Oct, sometimes longer in mild autumns).
• Whole-lawn overseed — autumn is far better than spring. The textbook combo is scarify + overseed + light feed in early September. Soil is warm, rain is reliable, weed pressure is low.

The engine waits for daytime temperatures averaging 10 °C+ over 5 days, no frost in the next 7-day forecast, and rain or irrigation due within 48 hours.

When not to seed

• Frost forecast in the next 7 days. Germinating seedlings are killed by a single hard frost.
• Drought or heatwave. Seed needs the top centimetre of soil moist for 14–21 days; impossible in heat without committed daily watering.
• Within 6 weeks of a selective herbicide. Most lawn herbicides suppress germination — the seed simply won't sprout.
• On waterlogged soil. Seed rots; or it floats away in the next downpour.
• November onwards for the whole-lawn job. Soil is cooling fast, germination is patchy, and the survival of any seedlings through winter is poor.
• Late June through August for the whole-lawn job. Heat stress kills more seedlings than it grows.

How to do it — patch repair

1. Scratch up the patch with a fork or rake until you see soil. Seed needs contact with soil; it won't take on top of dead grass or moss.
2. Remove debris — dead grass, stones, old roots. The seedbed should be loose, level, and clean.
3. Sprinkle seed (Family First for back lawns, Envy for fine turf) at the bag's stated rate for patch repair — typically somewhere between 25 and 50 g per square metre depending on the grass mix. Always follow the bag, not a generic number — different mixes (ryegrass, fescue, bent) want very different rates. A generous coverage but not a carpet — too dense and seedlings strangle each other.
4. Top with a thin layer of seed compost — 5–10 mm. This holds moisture and stops birds eating the seed. Garden soil works in a pinch.
5. Firm gently with the back of a rake. Just enough to make contact; don't compact.
6. Water lightly — a fine rose on a watering can. Soak, then check daily.
7. Keep moist for 14–21 days. This is the make-or-break step. Light watering 2–3 times a day until you see green shoots, then taper to once daily for two weeks.
8. First mow at ~50 mm when the new grass reaches 70–80 mm. Sharp blade, fast pass. Don't yank the seedlings out.

How to do it — whole-lawn overseed

1. Scarify first. This is the textbook autumn renovation combo. The scarifier opens up the thatch and creates the perfect seedbed.
2. Overseed at the bag's whole-lawn rate — typically around 20–35 g per square metre, but mix-dependent (fine-grass mixes like browntop go much lower). Always defer to the bag. Use a spreader for even coverage. Mowd's lawn-seed range includes Family First (hard-wearing, kid-and-pet-friendly) and Envy (showpiece-grade fine turf).
3. Light topdress — a thin layer of sandy loam or seed compost (3–5 mm). Optional but improves germination on heavy soils.
4. Light feed — a low-N "autumn lawn feed" or a starter feed (low-N, high-P). Skip if soil is already well-fed.
5. Water in. Light shower from a sprinkler if rain isn't due.
6. No mowing for 3 weeks. Let the seedlings establish before you cut them.
7. First mow — high (~40 mm) and gentle. Drop the height gradually over the next 2–3 cuts.

What to expect afterwards

Days 1–7: nothing visible. The seed is imbibing water and waking up.

Days 7–14: first green shoots appear, often patchy at first. Cool weather slows this; mild weather speeds it up. Looks scrappy.

Days 14–28: dense green fuzz across the patch. Seedlings reach mowable height. The ugliest phase is over.

4–8 weeks: the patch closes up and starts to blend with surrounding lawn. Colour will be a slightly lighter green for the first season — the new plants haven't built mature root systems yet. By the following spring, you can't tell where the patch was.

For whole-lawn overseed: expect 2–3 weeks of "the lawn looks worse" before it visibly thickens. The transformation is dramatic by the next May.

Common mistakes

• Letting the seedbed dry out, even once, in the first 14 days. This is the main reason patch-repair fails. Set a phone alarm.
• Sowing too thick. Seedlings strangle each other and the patch is patchy and weak.
• No soil contact. Seed sitting on top of dead grass won't germinate. Scratch the surface first.
• Mowing too early. Pulls the seedlings out. Wait until they're at least 70 mm.
• Forgetting birds. A thin compost top-layer is enough to deter most birds; without it, sparrows and pigeons eat half the seed.
• Using selective herbicide on overseed within 6 weeks. The herbicide suppresses germination and you waste the seed.

Seasonal notes

Spring: patch repair is fine. Whole-lawn overseed can work in late April–May, but autumn is still better.

Summer: patch repair only if you can commit to daily watering. Whole-lawn overseed: don't.

Autumn: prime time. Early September is the textbook moment for whole-lawn overseed. The combo of scarify + seed + feed + autumn rain is hard to beat.

Winter: don't. Wait for spring.

What do I need to seed a lawn?

A pre-seed fertiliser feeds the seedbed so new grass roots fast, and a quality seed matched to your lawn gives even, hard-wearing cover. Use the two together for the best strike rate.

Related Mowd guides: How to apply lawn seed · When to sow grass seed in summer

Frequently asked questions

When can I sow grass seed?

Soil needs to be reliably above about 8–10 °C and kept moist — in the UK that usually means spring and early autumn, with summer sowing possible if you can water consistently.

How do I stop birds eating grass seed?

Rake the seed lightly into the surface, apply a light topdressing, and keep the area moist. A pre-seed feed speeds germination so the seed is exposed for less time.

How often should I water new grass seed?

Keep the surface damp at all times until germination — usually a light watering once or twice a day in dry weather. Never let a germinating seedbed dry out.

Disclaimer

This is a general guide for typical UK domestic lawns. Different grass mixes germinate at different speeds and want different conditions. Read the bag's specific guidance on rate and depth. Patches under heavy shade, on poor soils, or in high-traffic areas may need a specialist mix or a non-grass solution.