Overseeding lawn seed for thin grass and bare patches
Updated: 21 October 2026
The lawn is still a lawn, but August left it threadbare, the moss came out in sheets, and two patches by the gate are down to soil. That is overseeding, not a new lawn from a bare bed. Seed thrown onto thatch sits there until the birds take it. A 10 kg bag bought for those two patches is the other mistake, because you then have most of a large lawn’s worth of seed in the shed. This page is the rate, the scarifying and the pack sizes that state an area. A brand-new bed of soil is on the [how to sow grass seed](/hub/seeds-and-plants/fast-growing-grass-seed/sub/fast-growing-grass-seed-how-to-sow) page. Prices sit on the [fast growing grass seed comparison](/hub/seeds-and-plants/fast-growing-grass-seed).
The lawn is still a lawn, but August left it threadbare, the moss came out in sheets, and two patches by the gate are down to soil. That is overseeding, not a new lawn from a bare bed.
The lawn is still a lawn, but August left it threadbare, the moss came out in sheets, and two patches by the gate are down to soil. That is overseeding, not a new lawn from a bare bed. Seed thrown onto thatch sits there until the birds take it. A 10 kg bag bought for those two patches is the other mistake, because you then have most of a large lawn’s worth of seed in the shed. This page is the rate, the scarifying and the pack sizes that state an area. A brand-new bed of soil is on the how to sow grass seed page. Prices sit on the fast growing grass seed comparison.
Our top picks
| Badge | Product | Stated area | Pack weight | Fit for overseeding | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Westland Gro-Sure Aqua Gel coated seed, 10 kg | 250 m² | 10 kg | A large thin lawn only | 8.3 | about £56.70 | View offer |
| Alternative |  Westland Gro-Sure multi purpose box, 10 m² | 10 m² | 300 g | A run of small patches | 7.4 | about £7.00 | View offer |
| Alternative |  WOLF Garten Wolf-Garten LR 25 reseeding seed | 25 m² | 499 g | Sold as reseeding seed | 8.4 | about £8.98 | View offer |
On this page
Overseeding is not a new lawn
Overseeding means you still have grass, and you are thickening it or filling patches. A new lawn is bare, firmed soil. The RHS, on repairing lawns, says sow a patch at the packet rate, usually about 15–25 g per square metre, with a light cover. Boston Seeds, a supplier, uses a similar band and allows more where the sward is very thin. A new lawn is often quoted at about 25–50 g per square metre, again as a supplier rule of thumb. The higher handful on two small patches wastes seed and can leave a coarse tuft.
Fast ryegrass will look different if the old lawn is a fine fescue. A brighter patch for a season is normal. If the thin area is shade under a tree, read the shade page before you overseed with a fast mix. Two patches of 1 metre by 1.5 metres are 3 square metres. At 25 g that is 75 g, a poor reason to open a 10 kg sack. A 60 square metre lawn at 20 g is 1.2 kg. That is a different purchase.
Open the soil, then sow
Seed has to touch soil. If you scatter it onto thatch, it germinates poorly or not at all. Mow a little shorter, then rake or scarify until you see soil. On a small patch, the RHS method is to cut out the dead mat, loosen the soil, sow, and cover lightly. One Gro-Sure review says seed on the surface and seed buried too deep both fail. A dusting of cover is enough.
Grassias buyers who raked dead grass describe a stronger take than the heatwave notes. An EverGreen review that scarified and still saw brown areas a week later shows that scarifying is not magic if the surface then dries. Keep the patches moist with a fine rose. Good Grow talks about two to three weeks of moisture after germination starts. Pair that with the RHS. Fleece or tape is more reliable than hoping a coating stops birds.
If you have just used a combined feed, weed and moss killer, wait. Raycox, a supplier, says about four weeks. That is a rule of thumb. The label on the product you used is the instruction that counts.
Packs in this set that state an area
Match the printed area to the thin area, then check the price on the main comparison. Gro-Sure’s multi purpose box states 10 m² from 300 g at £7.00, a sensible box for a run of patches. Quick GRO states 14 m² per 420 g box, sold as a pair at £10.76. UKgrow states 20 m² at £9.99 and is the only pack that names perennial ryegrass and red fescue. Wolf-Garten LR 25 states 25 m² at £8.98 and is sold as reseeding seed, with one review reporting German-only instructions.
The Gro-Sure 10 kg bag states 250 m² at £56.70. That is the best-value large pack on the best fast growing grass seed page when the thin area really is that big. It is the wrong sack for two patches. Grassias says up to 87.5 m² per 1.70 kg unit. Treat up to as a ceiling. EverGreen 480 g, the UKGROW 100 g tub, Doff 1 kg and the ProGrass bags print no coverage. You cannot choose them by square metres from the listing.
Mowing and use
Leave the new seedlings until they are about 5–7.5 cm, and take off about one third with a sharp blade. On a patch inside an older lawn, mow the established grass around it with care, or accept a slightly longer patch. Do not drag the mower across a muddy repair.
Keep dogs and children off the patches while the seed is loose and while the new plants are only a fortnight old. A small repair can take careful traffic sooner than a whole new lawn, and it still will not forgive a daily cut-through in the first month. If the thinness comes back every summer in the same shade, overseeding is a delay, not a cure. If water ponds on the patch, fix the level before you buy the next box.
Common questions
What is the difference between overseeding and a new lawn?
Overseeding thickens grass that is already there, or fills patches in it. A new lawn starts from bare, prepared soil. The how-to page is the bare-soil sequence. This page uses the lower repair rate and expects you to open the existing sward first. The two jobs do not share a sowing rate.
How many grams per square metre on thin grass?
Follow the packet. The RHS repair range is usually about 15–25 g per square metre. Boston Seeds, as a supplier guide, uses a similar overseeding band and allows more on a very thin sward. Three square metres at 25 g is only 75 g. Do not use a new-lawn rate of 25–50 g on a tiny patch unless the packet says to.
Do I have to scarify first?
You have to get seed onto soil. On a small patch, cutting out the dead mat and loosening the soil is enough. On a whole thin lawn, scarifying or a hard rake does that job. Seed left on thatch is the failure these reviews keep describing, including sows that were watered and still did not take.
Which pack size matches a few patches?
A stated small area: Gro-Sure’s 10 m² box, Quick GRO at 14 m² per box, UKgrow at 20 m², or Wolf at 25 m². The 10 kg, 250 m² Gro-Sure bag is for a large thin lawn. Packs with no printed area need the rate on the physical packet before you can match them to a measurement.
Can I overseed straight after moss killer?
Not if the product you used says otherwise. A supplier rule of thumb from Raycox is about four weeks after a combined feed, weed and moss killer. Read your label. Sowing into a fresh treatment is a common reason a careful rake still shows nothing. The four weeks is not a law.
When can I mow an overseeded lawn?
When the new grass is about 5–7.5 cm, and then only lightly, taking about a third. Mow the older grass so you are not forced to scalp the repair. Stay off the patch with games and dogs while it is still a mat of seedlings. From sowing through germination, the surface should not bake. Use a fine rose so you do not wash a small dose of seed into one corner.
Related pages
Sources
Sources taken from the research digest. Listings were checked in October 2026.
- RHS — Starting a lawn from seed (retrieved 21.10.2026)
- RHS — Lawns in shade (retrieved 21.10.2026)
- RHS — Repairing lawns (retrieved 21.10.2026)
- RHS — October lawns (retrieved 21.10.2026)
- RHS — Lawn drought care (retrieved 21.10.2026)
- Seed Marketing Regulations 2011 (retrieved 21.10.2026)
- GOV.UK — Certify seeds for marketing in England and Wales (retrieved 21.10.2026)
- Love The Garden — How to sow grass seed (retrieved 21.10.2026)
- Boston Seeds — Overseeding an existing lawn (retrieved 21.10.2026)
- amazon.co.uk listings for the twelve ASINs in this comparison (retrieved 21.10.2026)