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Onion Growing Guide
Allium family
Companion Planting
Growth Stages
- Seedling / Sprouting
- Leaf Growth / Bulbing
- Mature / Harvest Ready
Planting Dates by Zone
| Zone | Start Indoors | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 1a | Mar 16 | Apr 27 | Apr 27 | Jul 16 |
| Zone 1b | Mar 16 | Apr 27 | Apr 27 | Jul 16 |
| Zone 2a | Mar 6 | Apr 17 | Apr 17 | Jul 6 |
| Zone 2b | Mar 16 | Apr 27 | Apr 27 | Jul 16 |
| Zone 3a | Mar 13 | Apr 24 | Apr 24 | Jul 13 |
| Zone 3b | Mar 6 | Apr 17 | Apr 17 | Jul 6 |
| Zone 4a | Feb 24 | Apr 7 | Apr 7 | Jun 26 |
| Zone 4b | Feb 20 | Apr 3 | Apr 3 | Jun 22 |
| Zone 5a | Feb 17 | Mar 31 | Mar 31 | Jun 19 |
| Zone 5b | Feb 17 | Mar 31 | Mar 31 | Jun 19 |
| Zone 6a | Feb 17 | Mar 31 | Mar 31 | Jun 19 |
| Zone 6b | Feb 4 | Mar 18 | Mar 18 | Jun 6 |
| Zone 7a | Feb 4 | Mar 18 | Mar 18 | Jun 6 |
| Zone 7b | Jan 30 | Mar 13 | Mar 13 | Jun 1 |
| Zone 8a | Jan 25 | Mar 8 | Mar 8 | May 27 |
| Zone 8b | Jan 11 | Feb 22 | Feb 22 | May 13 |
| Zone 9a | Jan 9 | Feb 20 | Feb 20 | May 11 |
| Zone 9b | Dec 30 | Feb 10 | Feb 10 | May 1 |
| Zone 10a | Dec 12 | Jan 23 | Jan 23 | Apr 13 |
| Zone 10b | Nov 19 | Dec 31 | Dec 31 | Mar 21 |
| Zone 11a | Nov 19 | Dec 31 | Dec 31 | Mar 21 |
| Zone 11b | Nov 6 | Dec 18 | Dec 18 | Mar 8 |
| Zone 12a | Oct 23 | Dec 4 | Dec 4 | Feb 22 |
| Zone 12b | Oct 23 | Dec 4 | Dec 4 | Feb 22 |
| Zone 13a | Oct 23 | Dec 4 | Dec 4 | Feb 22 |
| Zone 13b | Oct 23 | Dec 4 | Dec 4 | Feb 22 |
Frequently Asked Questions
How long does it take to grow Onion?
Onion takes approximately 110 days from planting to harvest.
How much sun does Onion need?
Onion requires full sun (6+ hours direct sunlight per day).
How far apart should I plant Onion?
Plant Onion at 9/sqft (4" apart) using square foot gardening spacing.
Can Onion survive frost?
Onion is tolerant of moderate frost.
What are good companion plants for Onion?
Good companion plants for Onion include Strawberries, Cabbage, Beets, Lettuce, Carrots, Tomatoes. Avoid planting near Beans, Peas.
How long does Onion take to germinate?
Onion seeds germinate in 7-14 days at an optimal temperature of 70°F.
When should I start Onion seeds indoors?
Start Onion seeds indoors 10 weeks before your last frost date, then transplant -4 weeks after last frost.
Growing Tips
- Match day-length type to your latitude: short-day for south, long-day for north
- Start from transplants or sets for easiest growing
- Stop watering when tops begin to fall over naturally
Common Pests & Diseases
- Onion thrips
- Onion maggot
- Downy mildew
- Botrytis neck rot
Harvest Notes
Harvest when tops fall over and begin to brown. Cure in a warm, dry, airy spot for 2-3 weeks before storing.
Plan Your Onion Garden
Track Onion from seed to harvest with personalized frost dates, watering recommendations, and companion planting visualization.
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