root · transplant
Onion: how much to plant.
A family of 4 eating onion a few times a week needs about 11 plants in ~4 sq ft, worth about $11 a year at the store. Here are the exact numbers for your household, and when to plant in every zone.
How much to plant
Plants, space, seeds, and value.
Counts assume about 3 servings per person per week with a germination buffer built in. Store value uses ~$2.00/lb retail — an estimate that varies by region and season.
| Household | Plants | Bed space | Seeds to buy | Store value / yr |
|---|---|---|---|---|
| 1 person | 3 | ~1 sq ft | ~4 | ~$3 |
| 2 people | 6 | ~2 sq ft | ~8 | ~$6 |
| 4 people | 11 | ~4 sq ft | ~14 | ~$11 |
| 6 people | 17 | ~6 sq ft | ~22 | ~$17 |
Spacing
4" in row · 12" between rows
Sow depth
0.5"
Days to harvest
95 from transplant (110 from seed)
When to plant
Sow windows by USDA zone, 2026.
Zone dates are typical, not exact. The free planner uses your ZIP code's frost dates, not just the zone, and shifts every window to match.
| Zone | Spring sow window | Fall sow window |
|---|---|---|
| Zone 3 | Mar 7 – Apr 20 | — |
| Zone 4 | Mar 2 – Apr 15 | — |
| Zone 5 | Feb 20 – Apr 5 | — |
| Zone 6 | Feb 10 – Mar 26 | — |
| Zone 7 | Jan 26 – Mar 11 | — |
| Zone 8 | Jan 15 – Feb 28 | — |
| Zone 9 | Jan 1 – Jan 26 | — |
| Zone 10 | Jan 1 – Jan 6 | — |
Know before you grow
The practical stuff.
Yield
About 0.7 counts per plant over ~1 productive weeks (~0.5 lb).
Watch for
Onion thrips · Onion maggot · Downy mildew — the pest guide covers organic fixes for each, and Pest Radar shows what gardeners near you are reporting right now.
Neighbors
Plays well with carrot. Keep away from bush-bean, snap-pea.
On the plate (per 100 g, USDA)
40 kcal · 1.7 g fiber · 7.4 mg vitamin C · 146 mg potassium
Related varieties
Stop guessing. Get your exact numbers.
Tell the free planner what you want to eat and who you're feeding. It returns plant counts, spacing, and frost-safe sow dates for your ZIP code — not just your zone — in about 60 seconds.