Seed is sold by weight, but lawns are grown from seed counts — and different grasses have wildly different seeds per pound. That's why one bag's rate doesn't transfer to another, and why the number on the bag matters more than the number in your head.
New lawn vs overseeding
A new lawn starts from bare soil and every square inch has to be covered. Overseeding drops seed into existing turf to thicken it, so you only need roughly half — the grass that's already there is doing most of the work.
| Grass type | New lawn | Overseeding |
|---|---|---|
| Tall fescue | 6–8 lb / 1,000 sq ft | 3–4 lb |
| Kentucky bluegrass | 2–3 lb | 1–1.5 lb |
| Perennial ryegrass | 6–9 lb | 3–4 lb |
| Fine fescue | 4–5 lb | 2–2.5 lb |
| Bermuda (hulled) | 1–2 lb | 0.5–1 lb |
Our grass seed calculator takes your lawn dimensions, grass type and purpose and returns the pounds you need — and the cost, if you enter a price.
Why the rates differ so much
It's seed size, not seed quality. Kentucky bluegrass has roughly 2 million seeds per pound. Tall fescue has around 230,000. So a pound of bluegrass contains nearly nine times as many potential plants as a pound of fescue.
This is why a bag of bluegrass covers so much more ground, and why applying fescue rates to bluegrass wastes a lot of money and produces a worse lawn than doing it right.
Timing beats everything
You can do everything else perfectly and fail on timing. Grass seed germinates on soil temperature, not air temperature.
Cool-season grasses (fescue, bluegrass, rye): early autumn is far and away the best window. The soil is still warm from summer, the air is cooling, autumn rain does the watering, and — critically — weeds have stopped competing. Spring is a distant second, because your seedlings spend their first summer with immature roots.
Warm-season grasses (Bermuda, zoysia): late spring into early summer, once the soil is genuinely warm. The opposite calendar entirely.
Seed-to-soil contact is the whole game
Seed lying on top of thatch or matted grass will not germinate. It needs to physically touch soil.
For a new lawn, rake the surface loose. For overseeding, mow short, dethatch or core aerate first, and rake the debris off. Then broadcast at half rate in one direction and half in the perpendicular direction — a single pass always leaves stripes.
Rake lightly after sowing so seed settles into contact, but don't bury it. Grass seed needs light to germinate. A quarter inch of soil is plenty; an inch is a burial.
Watering is where most people lose it
New seed needs the top inch consistently damp — light watering two or three times a day, not one deep soak. A seed that germinates and then dries out is dead, and it doesn't get a second chance.
Keep that up for two to three weeks. Once it's up and you've mowed twice, shift to deep, infrequent watering to drive roots down.
Read the bag, not just the brand
Check the seed label for germination percentage (85%+ is good), weed seed content (under 0.5%), and "other crop" content. A cheap bag with 20% inert filler and poor germination isn't cheap — you're buying less grass per pound than the price suggests.
Try the free calculator
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Frequently Asked Questions
How much grass seed do I need per 1,000 sq ft?
It depends on type. Tall fescue needs 6 to 8 lb for a new lawn, Kentucky bluegrass only 2 to 3 lb because its seeds are far smaller. Overseeding uses about half.
What is the overseeding rate compared to a new lawn?
Roughly half. Overseeding thickens existing turf rather than covering bare soil, so the established grass is already doing most of the work.
Can I use too much grass seed?
Yes. Excess seed makes seedlings compete for water and light, producing thin, weak grass with shallow roots. The recommended rate is the correct rate.
When is the best time to plant grass seed?
Early autumn for cool-season grasses like fescue and bluegrass, and late spring to early summer for warm-season grasses like Bermuda. Soil temperature drives germination, not air temperature.