How Far Apart to Plant Onions
Set your conditions — the recommendation updates instantly.
GardenSays
Your 8×4 ft garden plot fits 72 onions at 4-inch spacing.
- Between plants
- 4 in
- Rows
- 3 @ 15 in
- Total plants
- 72
Onions need 3-4 inches between plants, in rows 12-18 inches apart so you can walk between them. At the 4-inch midpoint, that's 24 per row and 3 rows — 72 plants.
Calculated result · 1 verified source · Checked 2026-07-18 · How we decide
Why
Crowding is the most common spacing mistake: closer planting doesn't add yield, it adds shade, disease pressure, and small fruit. When in doubt, use the wider end of the range.
- Air circulation between mature plants is the cheapest disease prevention there is.
- Roots spread wider than the plant looks in June — spacing is set for August size.
When this doesn't apply
- UMN gives in-row spacing only; row spacing follows the site's standard intensive-bed convention for shallow-rooted crops of this size.
- Compact onions can take the tight end of the range; large or vigorous ones want the wide end.
- Square-foot gardening compresses further than these numbers — it trades yield per plant for yield per bed and needs diligent feeding.
How this was calculated
- 1. In-row spacing4 in
Onion: 3-4 inches between plants (extension guidance); midpoint used
- 2. Row layout24/row × 3 rows
Rows 12-18 inches apart (midpoint 15 in) so you can walk and harvest: 96÷4 per row, 48÷15 rows
- 3. Total72 plants
24 × 3
Data sources
- University of Minnesota Extension — Growing onions in home gardens — Thin seedlings to 3 to 4 inches apart. (checked 2026-07-18)
What changes this answer
Layout
Bed length (ft)
Set the value in the calculator above.
Bed width (ft)
Set the value in the calculator above.
Every change updates the answer, the math, the weekly steps and the share link instantly.
People also ask
When should I plant onions?
Direct-sow onions outside Apr 19 – Apr 26 — they shrug off frost. Calculate yours →
Your next decisions
More plant spacing tools: see all →