Wildflower Meadow Seed Calculator

How much wildflower seed do I need? Get the sowing rate, total seed weight, packets and cost from your own area & mix.

Area shape

Measuring within 10% is fine — seed isn't fussy.

Length

Width

Seed mix type Sowing density Sowing method

Currency

Seed price per kg

Packet size (for "packets needed")

Total wildflower seed needed

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Sowing rate

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Area

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Packets needed

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Estimated seed cost

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How to use this calculator

Pick your area shape and enter the measurements — or choose "I already know the area" and type it straight in.
Choose the seed mix you're buying. A pure (100%) wildflower mix is sown thinly; a meadow mix that includes grasses is sown more heavily.
Set the sowing density. Use the light rate over large areas or poor soil, and the generous rate for small, high-impact patches.
Tell it whether you're sowing onto bare soil or overseeding into existing grass — the latter needs about a third more seed.
Enter your seed price and packet size to see cost and how many packets to order. Switch units or currency any time — every figure re-converts.

What sowing rate should I use?

Seed merchants quote slightly different figures, but the typical ranges they publish are consistent:

100% wildflower mix (no grass): about 1–3 g/m². Often as low as 1 g/m² because the seeds are tiny and light.
Wildflower + grass meadow mix: roughly 4–5 g/m², because much of the weight is the grass component.
Annual mixes (poppies, cornflowers and similar): commonly around 5 g/m² for a dense first-year display.
Perennial / biennial mixes: typically 2–4 g/m².

For reference, 1 hectare = 10,000 m² and 1 acre ≈ 4,047 m², so a 2 g/m² rate is about 20 kg per hectare or roughly 8 kg per acre.

Why overseeding needs more seed

When you sow into an existing lawn or grass sward instead of bare, raked soil, fewer seeds reach the ground and germinate, and the established grass competes hard with seedlings. Growers commonly add around one third more seed to compensate. Scarifying, scalping the grass low, or slot-seeding first dramatically improves your strike rate — without that, results from broadcasting onto thick turf are often disappointing.

Common mistakes

Sowing too thickly. More seed isn't better — heavy rates let vigorous species and grasses crowd out the delicate wildflowers you actually want.
Skipping soil prep. Wildflowers favour low-fertility soil; a weed-free, firm, fine seedbed beats rich, fluffy compost.
Not bulking tiny amounts. Mixing fine seed with dry sand makes it far easier to spread an even, thin layer by hand.

Worked example

A 60 m² patch sown with a 100% wildflower mix at the standard 2 g/m² rate onto bare soil needs 60 × 2 = 120 g of seed. Choose to overseed instead and it rises by a third to about 160 g. At a seed price of £120/kg that's roughly £14–£19 of seed — exactly the kind of figure this tool keeps updated as you change any input.

FAQ

How much wildflower seed do I need per square metre?

A 100% wildflower mix is usually sown at about 1–3 g/m², while a wildflower-and-grass meadow mix is sown thicker at roughly 4–5 g/m². Annual-only mixes such as poppies and cornflowers are often sown around 5 g/m². This calculator multiplies your chosen rate by your measured area to give the exact total weight, then converts it to your preferred units.

Do I need more seed when overseeding into existing grass?

Yes. Sowing into an existing sward rather than cleared soil means poorer seed-to-soil contact and competition from established grass, so many growers add roughly one third more seed. Scarifying or slot-seeding first improves results. Select the overseeding option and the calculator adds this allowance for you automatically.

How many square metres are in an acre or hectare?

One hectare is exactly 10,000 square metres. One international acre is about 4,047 square metres (often rounded to 4,000 for quick estimates). Merchants frequently quote rates in kilograms per hectare or per acre, so converting your area helps you compare bag sizes and prices before ordering.

When is the best time to sow?

Autumn and spring are the traditional sowing windows in temperate climates. Autumn sowing suits perennial and biennial species that benefit from winter cold, while spring works well for annual displays. Whatever the season, sow onto a warm-enough, moist, weed-free seedbed and keep it from drying out while seedlings establish.

Method: total seed = area × the published rate for your selected mix and density, with a one-third uplift applied for overseeding. Rate ranges are drawn from UK and US wildflower seed suppliers and vary by product — always check the rate printed on your seed packet. Figures are an estimate for guidance only, not professional horticultural or agronomic advice.