How this calculator works
Row length divided by spacing estimates positions, rounded up separately for each row. A position is allocated a full spacing interval, unlike a grid with centres on both end boundaries. Direct-seed mode can add an establishment allowance; transplant mode counts final plants. Some UMN values describe dense sowing followed by thinning, so seed spacing is not always final plant spacing. Crops without a stage-specific preset use the local spacing field. Select Custom to override any preset.
Formula
Positions = rows × ceiling(row length/spacing). Seeds to obtain = ceiling(positions/establishment fraction). Transplants = positions.
Worked example
At a custom 10 cm spacing, two 10 m rows have 200 positions. With 80% establishment, obtain 250 seeds. Three 6 m rows at 50 cm transplant spacing need 36 plants.
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Frequently asked questions
Why do seed and transplant spacings differ?
Some vegetables are sown densely then thinned. Transplant spacing is usually the final retained distance.
What does the local spacing field do?
It is used for Custom or a crop without a preset for the selected stage. The result states which spacing was used.
Should I adjust a published sowing rate for germination again?
Only if it lacks an allowance. Enter 100% when the seed-packet sowing rate already compensates for expected losses.