root · transplant · advanced
Bulb Onion: how much to plant.
A family of 4 eating bulb onion a few times a week needs about 11 plants in ~4 sq ft, worth about $8 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 ~$1.50/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 | ~$2 |
| 2 people | 6 | ~2 sq ft | ~8 | ~$5 |
| 4 people | 11 | ~4 sq ft | ~14 | ~$8 |
| 6 people | 17 | ~6 sq ft | ~22 | ~$13 |
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 | Jul 21 – Sep 1 |
| Zone 4 | Mar 2 – Apr 15 | Jul 31 – Sep 11 |
| Zone 5 | Feb 20 – Apr 5 | Aug 10 – Sep 21 |
| Zone 6 | Feb 10 – Mar 26 | Aug 20 – Oct 1 |
| Zone 7 | Jan 26 – Mar 11 | Aug 30 – Oct 11 |
| Zone 8 | Jan 15 – Feb 28 | Sep 20 – Nov 1 |
| Zone 9 | Dec 13 – Jan 26 | Oct 10 – Nov 21 |
| Zone 10 | Nov 23 – Jan 6 | Oct 20 – Dec 1 |
Know when it's time to plant
Give us your ZIP and we'll email you a planting checklist for your exact frost dates, this month's list right now, then once a month when sow windows open.
One email a month, only when there's something to plant. Unsubscribe anytime.
Know before you grow
The practical stuff.
Ready to pick when
When about half the tops have yellowed and flopped over on their own, the bulbs are done sizing. Lift a week later and cure until the necks are papery.
Don't wait: Left in wet soil after the tops die, bulbs can rot or resprout.
Yield
About 0.7 counts per plant over ~1 productive weeks (~0.5 lb).
Watch for
Onion thrips · Onion maggot · Downy mildew · White rot, 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, beet, lettuce, tomato. Keep away from bush bean, pole bean, snap pea. Which of these hold up, and what not to plant after
On the plate (per 100 g, USDA)
40 kcal · 1.7 g fiber · 7.4 mg vitamin C · 146 mg potassium
Related varieties
When to plant bulb onion in your state
Pick your state for exact sow windows.
Each page keys bulb onionto that state's typical frost dates, with spring and fall windows and the indoor-start date where it helps.
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.
Onion, bulb keeps for months in cool storage. See how much to grow and store to feed your household, and how long it keeps.
Onion, bulb planting questions
How many bulb onion plants do I need per person?+
For steady eating (about 3 servings a week), plan on roughly 3 plants per person. A family of 4 needs about 11 plants, which takes around 4 sq ft of bed space.
How much space does bulb onion need?+
Space plants 4" apart in the row with 12" between rows. Sow 0.5" deep. Start indoors, transplant out.
When should I plant bulb onion?+
It depends on your frost dates. Spring sowing is keyed to your last spring frost. It also has a fall window keyed to your first fall frost. The zone table on this page shows typical windows; enter your ZIP in the free planner for dates tuned to your exact location, not just your zone.
Is growing bulb onion worth it?+
At about $1.50/lb retail and ~0.5 lb per plant, a family-of-4 planting is worth about $8 a year at the store. Prices vary by region and season, so treat it as an estimate.