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When to Plant Onion in Gulf County, FL

Gulf County, Florida Zone 9b May

Top priorities for Gulf County, Florida gardeners in May

Your garden in Gulf County, Florida is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost February 25
Avg. first frost November 28
Soil temp (4") 74°F
Watering Moderate
Pest pressure High
Daylight 13.5 hrs
  1. Basket week: onion

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

June prep starts now
  • First harvests: onion

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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.

Gulf County, Florida is in USDA Zone 9b. 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 313 feet, Gulf County receives approximately 51.7 inches of rainfall annually with predominantly sand soil. Summer highs average 92°F, providing good warmth for Onion during the growing season. 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.

Gulf County, FL (Zone 9b) Year-round
276 days
Last Spring Frost February 25
276 growing days
First Fall Frost November 28
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Gulf County Soil Profile

Soil Type

Sand

Soil pH

4.8-5.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (146 days to spare)
Start indoors: Jan 11 Transplant: Feb 8 🍅 Harvest: May 10 – Jun 28
Recommended (50%) ✓ Fits season (136 days to spare)
Start indoors: Jan 28 Transplant: Feb 25 🍅 Harvest: May 27 – Jul 15
Safe Start (90%) ✓ Fits season (137 days to spare)
Start indoors: Feb 17 Transplant: Mar 17 🍅 Harvest: Jun 16 – Aug 4

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 Gulf County

How your county's soil matches Onion's growing requirements.

Soil pH

Your soil pH (4.8–5.9) is more acidic than Onion prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

Sandy soil in Gulf 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 (1.4%). Add 2-3 inches of compost before planting Onion.

How to Plant Onion

1"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 1,272 gal / 100 sq ft

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" 0" ❄️ Dormant
Feb 4.3" 2.6" 1.7" 💧 Light watering
Mar 4.3" 3.1" 1.2" 💧 Light watering
Apr 4.3" 2.4" 1.9" 💧 Light watering
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 7.1" 0" ✅ Rainfall sufficient
Jul 4.3" 8.4" 0" ✅ Rainfall sufficient
Aug 4.3" 7" 0" ✅ Rainfall sufficient
Sep 4.3" 6.6" 0" ✅ Rainfall sufficient
Oct 4.3" 4.6" 0" ✅ Rainfall sufficient
Nov 4.3" 2.2" 2.1" 💧 Light watering
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (Feb–Nov in Gulf 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 needs ~1,995 GDD — county provides 5,263 GDD Excellent fit

Onion Planting Timeline — Gulf 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

MonthActivities
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
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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 9b

📆 Growing Season

276 days in Gulf County

Growing Tips for Onion in Gulf County

Direct sow Onion outdoors after February 25 in Gulf County when soil has warmed and frost danger has passed.

Sandy soil in Gulf County dries quickly — mulch Onion with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

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

  • Peas
  • Green Beans
  • Asparagus

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Onion in Gulf County, FL?

Gulf County is in Zone 9b 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 Gulf County, FL?

Gulf County, Florida is in USDA Hardiness Zone 9b. The average last spring frost is February 25 and first fall frost is November 28.

🌱

Your Gulf County Garden Planner — Free

A 24-page printable planner built for Gulf County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Gulf County, FL. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.