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35 lb of seed

Buy about 35 pounds of tall fescue seed for 5000 square feet. That is the full establishment rate of 7 lb per 1,000 sq ft. Sow half in one direction and half at right angles to it — that covers the gaps a single pass leaves.

  • Large seed, so it needs a high rate by weight. Deep roots and good drought tolerance.

Buying the right weight

Rates are for bulk seed. Divide by purity x germination — both printed on the bag — to get the weight of pure live seed you actually need. A bag at 95% purity and 85% germination needs about 24% more by weight than the rate says.

UMass advises raising the rate by about 50% in poor conditions — a rough seedbed, a late sowing, or ground that will be walked on while it establishes. That is 10.5 lb per 1,000 sq ft here.

In metric, 1 lb per 1,000 sq ft is about 4.9 g/m², so this rate is about 34.3 g/m².

Where this rate comes from

Covers Pennsylvania, New York and Nebraska. Rates for one grass differ several-fold between states — buffalograss is 1–2 lb per 1,000 sq ft in Kansas and 3–5 in Colorado — so check your own extension service before buying for a large lawn.

Penn State, Turfgrass Seed and Seed Mixtures (6-8); Nebraska, Overseeding in the Fall (3-4 overseed): https://extension.psu.edu/turfgrass-seed-and-seed-mixtures

Grass seed rates vary more between species than most people expect — by a factor of fifteen across the common ones — because seed size differs so much. This calculator uses per-species rates rather than a single average, for either a new lawn from bare soil or an overseed of existing turf.

How to use it

  1. Enter the lawn area. For an awkward shape, break it into rectangles and add them up, or measure the whole plot and subtract the house, drive and beds.
  2. Choose your grass. If you are overseeding and do not know what is there, match the climate: cool-season grasses in the northern US, Canada and the UK; warm-season in the southern US and Australia.
  3. Say what you are doing. Bare soil takes the full establishment rate; existing turf takes the lower overseeding rate.

How it is calculated

pounds of seed = rate (lb per 1,000 sq ft) x (area / 1000)

The whole question is which rate. Rates come from data/grass-seed-rates.ts, one figure per species for a new lawn and one for overseeding, and the note under the result explains anything particular about that grass.

A worked example

A 5,000 square foot lawn, new, in tall fescue:

  • Rate: 7 lb per 1,000 sq ft
  • Seed needed: 7 x (5,000 / 1,000) = 35 pounds

Overseeding the same lawn instead uses the lower rate of 5 lb per 1,000 sq ft, so 25 pounds. Switch the species to Kentucky bluegrass and the new-lawn figure drops to 12.5 pounds, because bluegrass seed is so much smaller that a pound goes far further.

Seeding rates by grass type

GrassSeasonNew lawnOverseeding
Kentucky bluegrassCool2.5 lb1.5 lb
Tall fescueCool7 lb5 lb
Fine fescueCool4.5 lb3 lb
Perennial ryegrassCool7 lb5 lb
Annual ryegrassCool9 lb6 lb
Creeping bentgrassCool1 lb0.5 lb
Bermudagrass, hulledWarm1.5 lb1 lb
ZoysiagrassWarm1.5 lb1 lb
CentipedegrassWarm0.4 lb0.25 lb
BahiagrassWarm6 lb4 lb
BuffalograssWarm4 lb2 lb

All figures are pounds per 1,000 square feet. These are typical published rates and worth checking against your own extension service, which will also give the right sowing window for your area.

Tips and common mistakes

Sow half in one direction and half at right angles. A single pass always leaves stripes. Two passes crossing each other is the simplest way to get even coverage from a spreader or by hand.

Keep the surface damp, not the soil soaked. Germinating seed dies if the top half inch dries out even once. That usually means a light watering once or twice a day for two or three weeks, not a deep soak every few days.

Do not fertilise heavily at sowing. A starter fertilizer with phosphorus helps root development, but a nitrogen-heavy feed encourages the weeds that are competing with your seedlings.

Check the seed label for coating and filler. Some products are a mix of seed, inert matter and mulch, so a given weight contains less actual seed than a bag of pure seed. The percentages are on the label.

Buy fresh seed. Germination falls off after a couple of years in storage, and a bargain bag of old seed is not a bargain.

Common questions

How much grass seed do I need for 1,000 square feet?
It depends entirely on the grass. Tall fescue and perennial ryegrass have large seeds and want around 7 pounds per 1,000 square feet for a new lawn. Kentucky bluegrass has much smaller seed and needs around 2.5 pounds for the same area. Centipedegrass is finer still at under half a pound. Always check the rate for your species rather than using a general figure.
Why is the overseeding rate lower than the new lawn rate?
Because you are filling gaps in existing turf rather than covering bare ground. Roughly two thirds of the establishment rate is typical. Sowing a full new-lawn rate into existing grass mostly wastes seed, because the seedlings compete with established plants and with each other.
Can I use more seed to get a thicker lawn faster?
No, and it usually backfires. Overseeding at double the rate crowds the seedlings, which then compete for water and light, grow spindly and become vulnerable to damping off. A correctly sown lawn thickens on its own as the plants tiller and spread.
When is the best time to sow grass seed?
For cool-season grasses, late summer to early autumn is the best window, with spring second — the soil is warm, the nights are cooling and there is less weed competition. Warm-season grasses want late spring to early summer, once soil temperatures are reliably warm. Sowing outside those windows is the most common reason a lawn fails to establish.
Do I need to cover the seed with soil?
Barely. Grass seed needs light contact with soil, not burial. Raking it in lightly so it sits in the top quarter inch, then rolling or treading it down, is enough. A thin scatter of compost or a seed blanket helps keep it damp. Seed buried an inch deep will not come up.
How long until grass seed germinates?
Perennial ryegrass is fastest, often in five to seven days. Tall and fine fescues take one to two weeks. Kentucky bluegrass is slow, two to three weeks, which is why it is often blended with ryegrass. Warm-season grasses from seed vary widely. Whatever the species, the top half inch of soil must stay damp throughout, which in warm weather means light watering once or twice a day.

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Written and checked by Muzamil Ali. Results are estimates — see the disclaimer.