Kentucky bluegrass needs 2–3 lb of seed per 1,000 sq ft for a new lawn. Tall fescue needs 6–8 lb. Perennial ryegrass falls in between at 6–10 lb. The differences come from seed size — a pound of KBG holds about 1.5 million seeds; a pound of tall fescue holds only around 225,000.
Seeding Rates by Species
| Species | Season | New seeding (lb/1,000 sq ft) | Overseeding (lb/1,000 sq ft) | Source |
|---|---|---|---|---|
| Kentucky bluegrass | Cool-season | 2–3 | 1–1.5 | Penn State Extension |
| Tall fescue | Cool-season | 6–8 | 3–4 | Purdue University Turfgrass |
| Perennial ryegrass | Cool-season | 6–10 | 3–5 | Oregon State University Extension |
| Fine fescue (creeping red, chewings, hard) | Cool-season | 3.5–5 | 2–3 | UC Cooperative Extension |
| Bermudagrass (seeded) | Warm-season | 1–2 | 0.5–1 | NC State Extension TurfFiles |
| Buffalograss | Warm-season | 1.5–2 | 1 | UC Cooperative Extension |
| Centipedegrass (seeded) | Warm-season | 1–2 | 0.5–1 | NC State Extension TurfFiles |
| Zoysia (seeded) | Warm-season | 1–2 | 0.5–1 | NC State Extension (plugs preferred) |
Sources: Purdue University AY-20-W; Cornell University Sports Field Seeding Rates; UC IPM Planting Times and Rates
Converting to Pounds Per Square Foot
Divide the per-1,000 sq ft rate by 1,000:
- Kentucky bluegrass: 2–3 lb/1,000 sq ft = 0.002–0.003 lb/sq ft
- Tall fescue: 6–8 lb/1,000 sq ft = 0.006–0.008 lb/sq ft
- Perennial ryegrass: 6–10 lb/1,000 sq ft = 0.006–0.010 lb/sq ft
Because these numbers require three decimal places to express clearly, extension programs universally publish rates per 1,000 sq ft — not per sq ft. Use the grass seed calculator to convert your lawn area to the seed quantity you need.
Worked Example: New Tall Fescue Lawn
You have 4,500 sq ft of bare soil to seed with tall fescue. Rate: 6–8 lb/1,000 sq ft.
- Low estimate: 4.5 x 6 = 27 lb
- High estimate: 4.5 x 8 = 36 lb
- Order 30–36 lb; seed at 15–18 lb per pass, making two perpendicular passes
A 10 lb bag covers 1,250–1,666 sq ft. You need 3 bags at the high rate.
Seed Mixtures and the Weight Trap
When two species are mixed (e.g., 80% KBG and 20% perennial ryegrass by weight), the actual seed count ratio is very different from the weight ratio. Per Cornell University:
A pound of KBG holds ~1.5 million seeds; a pound of perennial ryegrass holds ~250,000 seeds. A mix that is 70% PRG and 30% KBG by weight gives a roughly 50/50 count of seeds on the ground. Read bag labels carefully if species ratios matter for your lawn.
Overseeding Rates
Overseeding an existing lawn uses about half the new-seeding rate because you are adding to existing turf, not starting from bare soil. From University of Nebraska, overseeding rates:
- Kentucky bluegrass: ~2 lb/1,000 sq ft (vs. 2–3 for new seeding)
- Tall fescue: 3–4 lb/1,000 sq ft (vs. 6–8 for new seeding)
For overseeding best practices and timing, see overseeding guide.
Pure Live Seed (PLS) Adjustment
Bag labels list two key numbers:
- Purity %: the percentage of seed that is the correct species
- Germination %: the percentage of pure seed capable of germinating
PLS = Purity x Germination (both as decimals)
Example: A bag shows 95% purity, 85% germination. PLS = 0.95 x 0.85 = 0.81 or 81%.
To hit the target rate using this bag, divide the target rate by the PLS:
- Target: 8 lb/1,000 sq ft
- Adjusted: 8 / 0.81 = 9.9 lb/1,000 sq ft of product
This is the quantity of bag product to apply, not the number of viable seeds. Most bulk-sold seed and quality retail bags run 80–90% PLS.
Spreader Settings and Double-Pass Technique
Most bag labels list spreader settings only as a starting point — accuracy depends on your specific spreader model, its age, and the flow properties of the seed. Always calibrate before you start.
To calibrate:
- Weigh seed in the hopper at the start
- Run the spreader over a known area (a 20 x 50 ft strip = 1,000 sq ft)
- Weigh remaining seed; the difference is your actual rate per 1,000 sq ft
- Adjust the setting and repeat until the rate matches your target
Apply half the total seed in one direction, then the remaining half in a perpendicular direction. This technique, recommended by Purdue University Extension, reduces striping and uneven coverage.
Common Mistakes That Waste Seed
- Seeding before soil preparation: Seed applied on thatch, hard soil, or standing debris rarely germinates. A proper seedbed has loosened soil where seed can make direct contact.
- Applying at the high end on steep slopes: Slopes cause seed to wash into low spots before germination. Apply at the low end of the rate range on any slope steeper than 3:1 and use erosion-control netting on slopes steeper than 2:1.
- Using the nominal bag weight without checking PLS: A bag labeled for 2,000 sq ft at the standard rate may only cover 1,600 sq ft once the PLS adjustment is applied. Read the label’s guaranteed analysis table, not just the coverage claim.
- Over-seeding cool-season patches surrounded by warm-season grass: Cool-season grass seeded into an established bermuda or zoysia lawn must be at standard new-seeding rates, not overseeding rates, because bare soil is what it is establishing into — not into an existing cool-season stand.
Use the grass seed calculator to work out how many bags you need once you know your species and lawn area. For timing and soil temperature rules, see when to plant grass seed.