Garden Bed Plant and Seed Calculator
How many plants fit in your beds, and how many seeds to buy.
Part of the 🌾 Farmers toolkit, with more tools made for the job.
Leave empty for 1.
On the seed packet.
Leave empty for 100%. On the seed packet.
Gives the packets to buy.
Type the size of your beds and the spacing, and the plants and seeds you need appear here.
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Enter the size of your beds, how far apart the rows and plants should be, and the germination rate. This shows how many plants fit and how many seeds or packets you need.
The spacing for a crop is on the seed packet. This tool counts whole rows across the bed and whole plants along each row, which is what actually fits. Not every seed comes up, so it adds extra seeds for the germination rate on the packet.
How it’s worked out
- Rows across the bed: the bed width divided by the row spacing, rounded down to whole rows.
- Plants along a row: the bed length divided by the plant spacing, rounded down to whole plants.
- Plants per bed is rows times plants per row. Total plants is that times the number of beds.
- Seeds to buy is the total plants divided by the germination rate, rounded up. Packets is the seeds divided by the seeds in a packet, rounded up.
4 beds of 3 m by 1.2 m with rows 30 cm apart and plants every 15 cm fit 4 rows of 20 plants, which is 80 plants per bed and 320 in all. At 80% germination you need 400 seeds.
Common mistakes
- Using the spacing for a different crop. Check the packet for the crop and variety.
- Forgetting that rows near the edge need room. If the bed is narrow, fewer rows fit than the plain division suggests.
- Planting exactly the number you want. Allow for seedlings lost to slugs, birds and weather.
- Measuring the bed in one unit and the spacing in another. Beds are in metres or feet, spacing in centimetres or inches.
Questions
Where do I find the spacing and germination?
On the seed packet or the supplier's website. Germination is often shown as a percentage, and old seed germinates less well.
What if I sow two seeds per hole?
Then each plant uses two seeds. Double the seeds, or put 50% in the germination box as a rough guide.
Why does it round down the plants?
Because you cannot plant part of a plant. A bed 1.1 m wide with rows 30 cm apart fits 3 rows, not 3.7.
Can I use it for flowers?
Yes. It works for anything planted in rows at a set spacing.
Estimates only
These are estimates and general information, not agronomic, financial or professional advice. Yields, laying rates, feed amounts, prices and rainfall vary a lot, so use your own numbers and local advice.
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