How Much Straw for New Grass Seed? Bales by Lawn Size, and Straw vs Hay

Spread straw too thick over new grass seed and you can smother the seedlings you just paid for. Iowa State University Extension's rule: about half the soil should still show through, and one bale covers roughly 1,000 square feet. Clemson Extension gives the same rate and puts a bale at 60 to 80 pounds.

Quick pick: 1 bale of weed-free wheat straw per 1,000 sq ft, thin enough to see half the soil; a straw blanket on steep slopes.

Free calculator: pounds of grass seed for your lawn size: our free lawn seed calculator. No sign-up.

How much straw for new grass seed

At 1 bale per 1,000 sq ft (Clemson, Iowa State). Straw weight uses Clemson's 60 to 80 lb bale.

200 sq ft patch: 0.2 bale, 12 to 16 lb of straw. Buy 1 bale.

500 sq ft: 0.5 bale, 30 to 40 lb. Buy 1.

1,000 sq ft: 1 bale, 60 to 80 lb.

2,500 sq ft: 2.5 bales, 150 to 200 lb. Buy 3.

5,000 sq ft: 5 bales, 300 to 400 lb.

10,000 sq ft: 10 bales, 600 to 800 lb.

Bale sizes vary. Bagged seeding straw: use the coverage printed on the bag.

The math

☐ Area: length × width of each bare spot, in sq ft. Add the spots together.

☐ Bales = area ÷ 1,000, rounded up.

☐ Slopes: take steep areas out first and cover them with blankets. A 4 × 50 ft blanket covers 200 sq ft, so blankets = slope area ÷ 200, rounded up.

Example: a 30 × 40 ft backyard (1,200 sq ft) plus a separate 10 × 30 ft bank along the drive (300 sq ft).

Flat part: 1,200 ÷ 1,000 = 1.2, so 2 bales.

Bank: 300 ÷ 200 = 1.5, so 2 blankets.

How thick: the 50 percent rule

Iowa State: about 50 percent of the soil should be visible through the straw. Too much may smother emerging seedlings.

Clemson: straw lightly shades the seed and holds moisture so it doesn't dry out.

If seedlings turn yellow under the mulch, Clemson says to lightly rake some of it away.

Straw vs hay

Straw: the hollow stalks left after grain harvest, usually wheat, sometimes barley or oats (Piedmont Master Gardeners, Virginia Extension Master Gardener volunteers).

Hay: grasses, often with alfalfa, cut green as feed. Piedmont says most hayfields are full of weeds, and the farmer may have used a persistent herbicide.

Even straw isn't seed-free: leftover wheat can sprout (Piedmont). A Penn State turf article notes weed and grain seedlings in straw cut new turf seedling weights in one study.

Pick: straw sold as clean or weed-free. Clemson and Iowa State both specify weed-free straw.

After you spread it

☐ Roll the seeded area lightly before mulching for good seed-to-soil contact (Iowa State).

☐ Water right after mulching; keep the top inch of soil moist (Iowa State).

☐ On windy, sunny days, water 2 or 3 times (Iowa State).

☐ Rake the straw off once the grass is 1 to 1½ inches tall, or leave a thin layer to break down (Clemson).

☐ Steep slope? Iowa State calls erosion blankets excellent there.

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Straw over grass seed FAQ

How much straw do I need for grass seed?

About 1 bale per 1,000 sq ft (Clemson, Iowa State). 2,500 sq ft takes 2.5, so buy 3.

Should I use straw or hay on new grass seed?

Weed-free straw. Hay is cut as feed, and most hayfields are full of weeds (Piedmont Master Gardeners).

How thick should straw be over grass seed?

Thin enough that about half the soil shows (Iowa State).

When do I remove straw from new grass?

When the grass is 1 to 1½ inches tall, or leave a thin layer to decompose (Clemson).

Seeding late? Dormant seeding. Filling low spots first: topsoil to level a lawn. Spreading the seed: best broadcast spreader for a small lawn.

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Sources: Clemson HGIC 1203, 2024; Iowa State Extension, 2024; Piedmont Master Gardeners, 2023; G. Hamilton, Penn State, 1999.