DibbleWhen to plant Onion
Start onion seeds indoors 10 weeks before last frost, or use sets. Transplant 2 weeks before last frost, onions are hardy and size up with cool early growth.
When to plant Onion by zone
| Zone | Start seeds indoors | Sow or transplant | Harvest |
|---|---|---|---|
| Zone 3 | March 6 | May 1 | August 9 |
| Zone 4 | March 1 | April 26 | August 4 |
| Zone 5 | February 19 | April 16 | July 25 |
| Zone 6 | February 10 | April 7 | July 16 |
| Zone 7 | January 30 | March 27 | July 5 |
| Zone 8 | January 17 | March 14 | June 22 |
| Zone 9 | December 21 | February 15 | May 26 |
| Zone 10 | November 22 | January 17 | April 27 |
| Zone 11 | October 23 | December 18 | March 28 |
These dates use typical frost dates for each zone. Dibble tunes them to your exact ZIP and lets you adjust frost dates for your own yard.
Companion plants
Good neighbors for Onion:
Better kept apart:
Family and rotation
Onion is in the alliums family. Light feeders that deter pests. Good rotation partners; keep away from beans and peas. Learn about crop rotation.
Related crops
Garlic
When to plantChives
When to plantLeek
When to plantGreen Onion
When to plantShallot
When to plantTomato
When to plantQuestions
When should I plant onion?
It depends on your zone. Onion is a hardy crop, so the timing follows your last spring frost. Look up your zone in the table below for exact start, sow, and harvest dates, or open Dibble and enter your ZIP to get your own calendar.
How long does onion take to grow?
About 100 days from transplant to the first harvest, with a picking window of roughly 14 days after that.
What grows well with onion?
Good companions include Carrot, Beet, Lettuce, Tomato. Keep it away from Bean (bush), Pea.
Plant at the right time this season
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