Grass Seeding Rate Calculator

Calculate how much grass seed you need for new leys, reseeding, or overseeding

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Work in progress — this calculator is still under development and may not be fully accurate. Use results as a guide only.

Sward type & conditions

Long-term sward for mixed grazing — base rate 30 kg/ha

Multiplier: ×1

Field area & cost

12.36 acres

Adjusted seeding rate

30.0kg/ha

30 kg/ha base × 1 (seedbed) = 30.0 kg/ha

Total seed

150.0

kg

Base rate

30

kg/ha (AHDB)

25 kg bags

6

× 25 kg bags

20 kg bags

8

× 20 kg bags

Estimated seed cost

£675

at £4.5/kg × 150.0 kg

Rate adjustments

Base rate30 kg/ha
Seedbed (average)×1
Method (broadcast)×1
Adjusted rate30.0 kg/ha

About seeding rates: Base rates from AHDB grassland guidance for UK conditions. Overseeding rates are lower because the existing sward provides some establishment. For oversown swards, consider scarifying or slot-seeding to improve seed-to-soil contact. Direct drilling requires ~20% more seed to account for lower germination uniformity compared to a consolidated seedbed.

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