When to Plant Onion in USDA Zone 9a
Zone 9a gardeners: here's your June plan
Welcome to June in Zone 9a. These are the moves that will have the biggest impact on your growing season.
-
Bring in the onion
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
Get ahead of July
- First harvests: onion
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
In Zone 9a, the average last spring frost is around February 10 and the first fall frost is around December 10, giving you a growing season of approximately 303 days.
Onion Planting Timeline — Zone 9a
Where Is USDA Zone 9a?
The map below highlights the states that contain Zone 9a. Click any state to see the Onion planting schedule for that location.
Onion Planting Calendar — Zone 9a
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 13 | Jan 13 – Jan 27 |
| Transplant Outdoors | February 10 | Feb 10 – Feb 24 |
| Direct Sow | January 20 | Jan 20 – Feb 10 |
| Harvest | May 12 | May 12 – Jun 30 |
| Fall Sowing | October 15 | Oct 15 – Oct 29 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors Direct Sow |
| February | Transplant Outdoors Direct Sow |
| March | — |
| April | — |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Free Zone 9a Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 9a with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
Days to Maturity
90–120 days
Soil pH
6 – 7
Zone Temperature Range
20°F to 25°F average annual minimum
Growing Season
303 days (Zone 9a average)
Planting Specifications
| Planting Depth | 1 inches |
| Plant Spacing | 6 inches apart |
| Row Spacing | 12 inches between rows |
Growing Tips for Onion in Zone 9a
Zone 9a offers a long growing season (~303 days). You can plant Onion earlier and may get multiple harvests.
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
The Gardener's Encyclopedia to Companion Planting
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Saving Onion Seeds
Recommended for Your Garden
Reduce heat stress and sun scorch in hot climates with UV-stabilized shade cloth.
Start seeds indoors with reusable cell trays and humidity domes.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Related Plants
Onion in Other Zones
Onion by State
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Onion in Zone 9a?
In Zone 9a, plan your Onion planting around the average last frost date of February 10. Start seeds indoors around January 13. Direct sow outdoors around January 20. Transplant seedlings around February 10.
Can Onion grow in Zone 9a?
Yes, Onion can grow well in Zone 9a, hardy in USDA zones 3a through 10b. Zone 9a has a growing season of approximately 303 days, which is sufficient for Onion (90-120 days to maturity).
When can I harvest Onion in Zone 9a?
In Zone 9a, expect to harvest Onion from May 12 – June 30. Onion takes 90-120 days from planting to harvest.
What is the last frost date for Zone 9a?
The average last spring frost in Zone 9a is around February 10, and the first fall frost is around December 10. This gives a growing season of approximately 303 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Onion?
Good companion plants for Onion include Carrots, Lettuce, Beets, Cabbage. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 9a Garden Planner — Free
A 22-page printable planner tailored to Zone 9a. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.