Topdressing Calculator
Grass Seed Calculator UK
Work out exactly how much grass seed you need
For new lawns, overseeding, or patch repairs. Draw your lawn on the map or enter your area manually.
Built with 30+ years of professional turf experience
Find & Draw Your Lawn
Search for your address, then draw your lawn boundary on the satellite view
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Seed Calculator
Based on your lawn measurements
Your Lawn Area
0
square metres
What Are You Doing?
New Lawn (bare soil)
Starting from scratch
35 g/m²
Overseeding
Thickening up existing grass
20–35 g/m²
Patch Repair
Filling bare spots
40 g/m²
How Does Your Lawn Look?
Mostly Bare
35 g/m²
Thin & Patchy
25 g/m²
Needs Thickening
15 g/m²
You need
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Give Your Seed the Best Start
Seed is only half the job — feeding the seedlings and conditioning the soil is what gets a thick lawn established fast.
Seed & Establish Pro
Pre-seeder fertiliser — high phosphorus drives root development in new seedlings. Apply before or at sowing.
Seaweed Lawn Booster
8% Ascophyllum nodosum — conditions the soil and helps new roots establish faster. The year-round constant.
Bundle & Save 10%
A starter feed drives root growth, and seaweed conditions the soil the seedlings are growing into. Sized automatically from your calculation above — or enter an area here.
m²
Bundles are sized at the standard feed rate of 30g/m² and 2ml/m² of seaweed. Discount applies automatically at checkout.
Get the real answer for YOUR soil
Seed germinates by soil temperature, not the calendar. Check yours before you sow:
UK Grass Seed Rates by Type
A quick reference for common UK grass seed types. These are typical rates. Always check the specific product you're using.
| Grass Type / Mix | New Lawn (g/m²) | Overseeding (g/m²) | Best For |
|---|---|---|---|
| Dwarf Perennial Ryegrass Most Common |
30–35 | 20–25 | Family lawns, high traffic |
| Hard-Wearing Ryegrass Mix | 35–40 | 20–25 | Kids, dogs, heavy use |
| Fine Fescue Mix (Ornamental) | 30–35 | 15–20 | Low traffic, display lawns |
| Fescue & Bent (Traditional Fine) | 30–35 | 15–20 | Luxury lawns, cylinder mowing |
| Shade & Difficult Areas Mix | 30–35 | 20–25 | Under trees, north-facing gardens |
| Pure Bent Grass (Agrostis) | 8–10 | 4–5 | Golf greens, bowling greens |
| Wildflower & Grass Mix | 3–5 | 2–3 | Meadow areas, wildlife |
Rates based on UK trade guidelines. We recommend 30 g/m² as a good all-round starting point for most dwarf ryegrass mixes (range 25–35 g/m²).
Seed Questions, Answered
When your soil is consistently above 8°C — typically mid-spring or early autumn in the UK. Autumn is often the sweet spot: warm soil, more moisture, less weed competition. Use the soil temperature checker on this page for your local reading.
A starter fertiliser like Seed & Establish Pro is high in phosphorus, which drives root development in new seedlings. Apply it before or at the time of sowing. It gives your new grass the best possible start. Once established, switch to a seasonal feed like Spring Starter Plus or Autumn Lawn Builder.
Ryegrass mixes typically show in 7–14 days in warm, moist soil. Fescues are slower — 14–21 days. Cold soil stretches everything out, which is why sowing into rising soil temperatures always beats forcing it early.
Yes — consistent moisture is the single biggest factor in germination. The seed bed should stay damp (not waterlogged) until the new grass is established. A light watering daily in dry spells beats an occasional soaking.
Buy by specification rather than brand: look for DEFRA-certified seed, and for most domestic lawns a dwarf perennial ryegrass mix is the right call — quick to establish and hard-wearing.
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