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BULB VEGETABLE

Onion

Allium cepa

Onions can be established from seed, sets or transplants. Bulb formation responds to day length, so cultivar choice needs regional context. [1][2]

Plant
Onion
Category
Bulb vegetable
Spacing
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SOURCE-BACKED GUIDANCE

Plant spacing

Use onion spacing that matches direct seeding or transplanting and account for cultivar response to day length.

Direct-sown onions

Plant spacing
3–4 in after thinning
Row spacing
12–18 in

University of Minnesota guidance for direct-seeded garden rows. [1]

Transplanted onions

Plant spacing
3–4 in
Row spacing
12–16 in

University of Minnesota guidance for transplants. [1]

Growing-method context

Seed, sets and transplants are distinct establishment methods; follow the method-specific directions supplied for the material you use. [1][2]

Planning notes

Do not turn a source's regional planting calendar into a global date. Day-length adaptation and local conditions affect cultivar choice. [1][2]

TURN GUIDANCE INTO A LAYOUT

Use the Plant Spacing Calculator

Choose the source entry that matches your plant and growing method, then enter that spacing yourself. The calculator applies only the geometry you provide.

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Sources

  1. University of Minnesota Extension: Growing onions in home gardensReviewed by Grownestia 2026-09-08
  2. Royal Horticultural Society: How to grow onionsReviewed by Grownestia 2026-09-08