When to Plant Onion in Franklin County, FL
What to do in May
Welcome to May in Zone 9a. These are the moves that will have the biggest impact on your growing season.
-
Basket week: onion
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
June will be here before you know it — start on
- 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.
Franklin County, Florida is in USDA Zone 9a. The average last spring frost is February 25 and the first fall frost is November 28, giving you a growing season of approximately 276 days.
At an elevation of 487 feet, Franklin County receives approximately 59.9 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.
Franklin County Soil Profile
Soil Type
Sand
Soil pH
4.9-6
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.
Soil Compatibility in Franklin County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (4.9–6.0) is more acidic than Onion prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
Sandy soil in Franklin County warms quickly in spring but drains fast. Onion will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Drainage is adequate for Onion.
Organic Matter
Organic matter is low (1.6%). Add 2-3 inches of compost before planting Onion.
How to Plant Onion
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Plant Water Budget
Monthly Watering Guide for Onion
Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Onion Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.6" | 0" | ❄️ Dormant |
| Feb | 4.3" | 2.8" | 1.5" | 💧 Light watering |
| Mar | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Apr | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| May | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jun | 4.3" | 7.6" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 9.2" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 10" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 7.4" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 4.9" | 0" | ✅ Rainfall sufficient |
| Nov | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Dec | — | 2.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Franklin County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Onion Planting Timeline — Franklin County, FL
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 28 | Jan 28 – Feb 11 |
| Transplant Outdoors | February 25 | Feb 25 – Mar 11 |
| Direct Sow | February 4 | Feb 4 – Feb 25 |
| Harvest | May 27 | May 27 – Jul 15 |
| Fall Sowing | October 3 | Oct 3 – Oct 17 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Transplant Outdoors Direct Sow |
| March | Transplant Outdoors |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 9a
📆 Growing Season
276 days in Franklin County
Growing Tips for Onion in Franklin County
Direct sow Onion outdoors after February 25 in Franklin County when soil has warmed and frost danger has passed.
Sandy soil in Franklin County dries quickly — mulch Onion with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
With summer highs reaching 96°F in Franklin County, provide afternoon shade for Onion and water deeply in the morning.
Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Franklin County, FL?
Franklin County is in Zone 9a with an average last frost of February 25. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Franklin County, FL?
Franklin County, Florida is in USDA Hardiness Zone 9a. The average last spring frost is February 25 and first fall frost is November 28.
Your Franklin County Garden Planner — Free
A 24-page printable planner built for Franklin County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.