How to grow onions in a raised bed
Plant small bulbs ("sets") pointy end up. Harvest when the tops fall over.
Spacing9 plants per square foot
How to startSow seeds right in the bed
When to plantAbout 4 weeks before your last spring frost
Time to harvestAbout 100 days
Grows toAbout 16 in tall
When to plant onions in your zone
Dates are based on the average frost dates for each zone. Don't know your zone? Enter your ZIP code in the planner.
| Zone | Start seeds indoors | Plant in the bed | Plant again for fall |
|---|---|---|---|
| Zone 3a | — | Apr 22 | — |
| Zone 3b | — | Apr 17 | — |
| Zone 4a | — | Apr 14 | — |
| Zone 4b | — | Apr 10 | — |
| Zone 5a | — | Apr 6 | — |
| Zone 5b | — | Mar 31 | — |
| Zone 6a | — | Mar 25 | — |
| Zone 6b | — | Mar 18 | — |
| Zone 7a | — | Mar 11 | — |
| Zone 7b | — | Mar 4 | — |
| Zone 8a | — | Feb 25 | — |
| Zone 8b | — | Feb 15 | — |
| Zone 9a | — | Feb 1 | — |
| Zone 9b | — | Jan 18 | — |
| Zone 10a | — | Jan 3 | — |
| Zone 10b | — | Dec 18 | — |
Tips for raised beds
- In square-foot gardening, plant 9 plants in each 1 × 1 ft square.
- It stays fairly short, so it can go near the south (sunny) edge of the bed.
- Most vegetables and fruit need at least 6 hours of direct sun a day.
Where to buy onion seeds
Burpee · True Leaf Market · Botanical Interests
Plan where your onions go. Pick your bed size and material, choose your plants, and get a printable plan with measurements, a shopping list and planting dates for your ZIP code. Free, no sign-up.
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