How it works
The formula
pounds = area ÷ 1,000 × seeding rate
bags = the 3, 7, 20 lb bags that hold the pounds with the least seed left over
Assumptions
- New-lawn rates sit inside the ranges in university extension guides: Purdue Extension (AY-25-W) gives Kentucky bluegrass 2 lb and turf-type tall fescue 6 to 9 lb per 1,000 sq ft. The University of Kentucky (AGR-52) gives tall fescue 6 lb and fine fescues 4 to 6 lb. Ohio State (Buckeye Turf) gives perennial ryegrass 7 to 8 lb. We use one value per type: Kentucky bluegrass 2.5, Tall fescue 7, Perennial ryegrass 7, Fine fescue 5, Bermudagrass, uncoated seed 1, Sun and shade mix 5.5 lb.
- Bermudagrass is about 1 lb per 1,000 sq ft of uncoated seed, per the University of Kentucky; coated seed is mostly coating, so use twice as much (2 lb). The sun and shade mix is our blend of the bluegrass and fine fescue rates. Overseeding rates are our allowance, about half to two thirds of the new-lawn rate, since no extension table gives exact figures. Always follow the rate printed on your bag, which depends on the blend.
- Straw cover is about 1 bale per 1,000 sq ft, spread thin enough that soil still shows through. This is a common lawn-care figure, not an extension number. Some guides use up to 2 bales.
- Seed comes in bags of 3, 7, 20 lb and larger. We pick the bags that cover the pounds with the fewest pounds bought (extra seed costs money), then the fewest bags, and never more than 4 of the 3 lb size. Cost is your per-lb price times the pounds you buy.
- Metric: type meters. The lawn is converted to feet for the math, areas show in m² with sq ft beside them, and seed stays in pounds.
Worked example
A 50 × 40 ft lawn, new, tall fescue
- Area: 50 × 40 = 2,000 sq ft
- Rate: 7 lb per 1,000 sq ft
- Pounds: 2,000 ÷ 1,000 × 7 = 14.00 lb
- Bags: two 7 lb bags = 14 lb
- Straw: 2,000 ÷ 1,000 = 2.00, so 2 bales
- Seed at $3 to $9 per lb on 14 lb: $42 to $126
Seed bags come in odd sizes, so you often buy more than you need. For 23 lb the best buy is one 20 lb bag + one 3 lb bag. Leftover seed keeps for a season or two in a cool, dry place, so a bigger bag is rarely wasted.
Pounds of seed by lawn size, new lawn
| Lawn size | Kentucky bluegrass | Tall fescue | Perennial ryegrass | Fine fescue |
|---|---|---|---|---|
| 1,000 sq ft | 2.5 lb | 7 lb | 7 lb | 5 lb |
| 2,000 sq ft | 5 lb | 14 lb | 14 lb | 10 lb |
| 5,000 sq ft | 12.5 lb | 35 lb | 35 lb | 25 lb |
| 10,000 sq ft | 25 lb | 70 lb | 70 lb | 50 lb |
New-lawn rates: Kentucky bluegrass 2.5, Tall fescue 7, Perennial ryegrass 7, Fine fescue 5 lb per 1,000 sq ft. These are pounds needed, before rounding up to bags.
Questions people ask
How much grass seed do I need per 1,000 sq ft?
It depends on the grass. For a new lawn we use 2.5 lb of kentucky bluegrass, 7 lb of tall fescue, 7 lb of perennial ryegrass, 5 lb of fine fescue, 1 lb of bermudagrass, uncoated seed, 5.5 lb of sun and shade mix. Your 2,000 sq ft lawn needs 14.00 lb of tall fescue, bought as two 7 lb bags.
How much less seed does overseeding take?
About half. Overseeding only adds seed to a lawn that is already there, so we use 3.5 lb per 1,000 sq ft for tall fescue against 7 for a new lawn. For 2,000 sq ft that is 7.00 lb instead of 14.00 lb. Overseeding rates are a rule of thumb; check your bag.
When is the best time to plant grass seed?
Extension guides agree on the pattern. Cool-season grasses (bluegrass, fescue, ryegrass) do best seeded in late summer to early fall, when soil is warm and weeds are fading, with spring as a second choice. Warm-season grasses such as bermudagrass go in late spring to early summer, once the soil is reliably warm. Check your state extension office for exact dates.
Do I need straw over grass seed?
On a new lawn it helps: straw holds moisture, shields seed from birds and washing rain, and still lets light through. Use straw, not hay, which carries weed seed. Spread it thin so soil still shows. For 2,000 sq ft that is 2 bales. It is not needed when overseeding into an existing lawn.
How long does grass seed last?
Stored dry and cool in a sealed container, seed stays usable for a season or two, with germination falling over time. Check the test date on the bag and use older seed at a slightly heavier rate. Seed left in the sun, damp or hot garage loses viability faster.