When to Plant Onion in Polk County, FL
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.
Polk County, Florida is in USDA Zone 9b. The average last spring frost is January 25 and the first fall frost is December 19, giving you a growing season of approximately 328 days.
At an elevation of 236 feet, Polk County receives approximately 58.3 inches of rainfall annually with predominantly sand soil. Summer highs average 96°F, so Onion may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Onion will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Onion root diseases.
Polk County Soil Profile
Soil Type
Sand
Soil pH
4.9-6.3
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Plant Water Budget
Onion Planting Timeline — Polk County, FL
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 28 | Dec 28 – Jan 11 |
| Transplant Outdoors | January 25 | Jan 25 – Feb 8 |
| Direct Sow | January 4 | Jan 4 – Jan 25 |
| Fall Sowing | October 24 | Oct 24 – Nov 7 |
| Harvest | April 26 | Apr 26 – Jun 14 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors Transplant Outdoors Direct Sow |
| February | Transplant Outdoors |
| March | — |
| April | Harvest |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | Fall Sowing |
| December | Start Indoors |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
90–120 days
Soil pH
6 – 7
USDA Zone
Zone 9b
Growing Season
328 days
Growing Tips for Polk County
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
Level Up Your Garden
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Polk County, FL?
Polk County is in Zone 9b with an average last frost of January 25. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Polk County, FL?
Polk County, Florida is in USDA Hardiness Zone 9b. The average last spring frost is January 25 and first fall frost is December 19.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Polk County gardeners in Zone 9b organize planting dates, track what's growing, and never miss a planting window.
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