Grass Seed Calculator

It depends on the grass. For a new lawn, typical rates are about 2 to 3 lb of Kentucky bluegrass, 6 to 8 lb of tall fescue, 5 to 8 lb of perennial ryegrass and 4 to 5 lb of fine fescue per 1,000 sq ft. Overseeding takes roughly half to two thirds of that. The rate on your bag is the one to follow.

An acre is 43,560 square feet, so multiply your rate per 1,000 sq ft by 43.56. At 7 lb per 1,000 sq ft (tall fescue) that is about 305 lb, and at 2.5 lb (Kentucky bluegrass) it is about 109 lb. Add a little extra for waste.

Divide the bag weight by the rate and multiply by 1,000. At 7 lb per 1,000 sq ft a 50 lb bag covers about 7,100 sq ft, and at 2.5 lb per 1,000 sq ft it covers about 20,000 sq ft. Coverage printed on the bag is usually for the label rate.

Use the overseeding rate for your grass, which is lower than for a new lawn because there are already plants there. For example, tall fescue is overseeded at about 4 to 6 lb per 1,000 sq ft. Mow short, rake out thatch, and make sure seed touches the soil.

Too much seed crowds the seedlings, which compete for water and light and are more prone to disease. Too little leaves thin patches where weeds move in. Measure the area, pick the rate on the label and spread it evenly in two passes.

Cool-season grasses do best when seeded in late summer to early fall, with early spring as a second choice. Warm-season grasses are usually seeded in late spring to early summer, when the soil has warmed to about 65 to 70°F. Local climate varies, so check with your extension service.

Perennial ryegrass can sprout in 5 to 10 days, tall fescue in 7 to 14, and Kentucky bluegrass in 14 to 30. Warm-season seed is often slower. Keep the top inch of soil damp until the grass is established, and wait to mow until it is tall enough.

Seed needs good contact with the soil, so lightly rake it in and roll or press it. Covering it with a thin layer of straw or compost, about a quarter inch at most, helps keep it moist. Burying seed deeper can stop it coming up.

For a new lawn, 5,000 sq ft takes about 30 to 40 lb of tall fescue (6 to 8 lb per 1,000), about 10 to 15 lb of Kentucky bluegrass (2 to 3 lb) or 25 to 40 lb of perennial ryegrass (5 to 8 lb). Overseeding takes about half to two thirds of that.

For a new lawn, 10,000 sq ft takes about 60 to 80 lb of tall fescue, 20 to 30 lb of Kentucky bluegrass or 50 to 80 lb of perennial ryegrass. For overseeding tall fescue at 4 to 6 lb per 1,000 sq ft, it is 40 to 60 lb. Add about 10% for waste.

A quarter acre is about 10,890 square feet. At 6 to 8 lb per 1,000 sq ft, tall fescue needs about 65 to 87 lb, and at 2 to 3 lb per 1,000 sq ft Kentucky bluegrass needs about 22 to 33 lb. The lawn probably does not cover the whole lot, so measure only the grass.

Measure the bare area and use the overseeding rate for your grass. A 3 × 3 ft patch is 9 square feet, so tall fescue at 5 lb per 1,000 sq ft needs just 0.045 lb, which is about 0.7 oz. A small amount of seed goes a long way, so weigh it or use a handful per square foot as a rough guide.

Seed costs much less and offers more variety, but it takes weeks to sprout and needs steady watering, and it is best sown at the right time of year. Sod gives an instant lawn and can go down more widely through the year, but it costs more. Use the sod calculator to compare for your lawn size.

Wait until the grass is tall enough, usually about 3 to 4 inches for cool-season lawns, and never remove more than a third of the blade height at once. Keep the mower blade sharp and avoid wet ground. Limit foot traffic until the lawn is well rooted.

Seeds differ in size. Kentucky bluegrass seeds are tiny, over a million to the pound, while tall fescue seeds are bigger, roughly 200,000 to 250,000 to the pound. A pound of bluegrass therefore covers far more ground, which is why its rate per 1,000 sq ft is lower.