Blog

When to Plant Onion in Sarasota County, FL

Sarasota County, Florida Zone 10a May

Your May planting checklist for Sarasota County, Florida

Your Sarasota County, Florida garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost February 3
Avg. first frost December 22
Soil temp (4") 80°F
Watering Moderate
Pest pressure High
Daylight 13.3 hrs
  1. Pick onion

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

June will be here before you know it — start on
  • First harvests: onion

Instant PDF download. No spam, unsubscribe any time.

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.

Sarasota County, Florida is in USDA Zone 10a. The average last spring frost is February 3 and the first fall frost is December 22, giving you a growing season of approximately 322 days.

At an elevation of 67 feet, Sarasota County receives approximately 58.8 inches of rainfall annually with predominantly sand soil. Summer highs average 85°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.

Sarasota County, FL (Zone 10a) Year-round
322 days
Last Spring Frost February 3
322 growing days
First Fall Frost December 22
Share this guide:

Sarasota County Soil Profile

Soil Type

Sand

Soil pH

5-5.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (191 days to spare)
Start indoors: Dec 26 Transplant: Jan 23 🍅 Harvest: Apr 24 – Jun 12
Recommended (50%) ✓ Fits season (182 days to spare)
Start indoors: Jan 6 Transplant: Feb 3 🍅 Harvest: May 5 – Jun 23
Safe Start (90%) ✓ Fits season (156 days to spare)
Start indoors: Feb 3 Transplant: Mar 3 🍅 Harvest: Jun 2 – Jul 21

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 Sarasota County

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

Soil pH

Your soil pH (5.0–5.8) is more acidic than Onion prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

Sandy soil in Sarasota 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 (1.5%). 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 1,539 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 2.8" 0" ❄️ Dormant
Feb 4.3" 3.1" 1.2" 💧 Light watering
Mar 4.3" 3.3" 1" 💧 Light watering
Apr 4.3" 2.6" 1.7" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 8.2" 0" ✅ Rainfall sufficient
Jul 4.3" 9.7" 0" ✅ Rainfall sufficient
Aug 4.3" 7.4" 0" ✅ Rainfall sufficient
Sep 4.3" 8.4" 0" ✅ Rainfall sufficient
Oct 4.3" 5.3" 0" ✅ Rainfall sufficient
Nov 4.3" 2.2" 2.1" 💧 Light watering
Dec 4.3" 2.1" 2.2" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in Sarasota 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 ~1,444 GDD — county provides 4,441 GDD Excellent fit

Onion Planting Timeline — Sarasota County, FL

Onion Planting Calendar

Activity When Date Range
Start Indoors January 6 Jan 6 – Jan 20
Transplant Outdoors February 3 Feb 3 – Feb 17
Direct Sow January 13 Jan 13 – Feb 3
Harvest May 5 May 5 – Jun 23
Fall Sowing October 27 Oct 27 – Nov 10

Plant 1" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors Direct Sow
February Transplant Outdoors Direct Sow
March
April
May Harvest
June Harvest
July
August
September
October Fall Sowing
November Fall Sowing
December
Share this guide:

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 10a

📆 Growing Season

322 days in Sarasota County

Growing Tips for Onion in Sarasota County

Direct sow Onion outdoors after February 03 in Sarasota County when soil has warmed and frost danger has passed.

Sandy soil in Sarasota 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 Sarasota County, FL?

Sarasota County is in Zone 10a with an average last frost of February 3. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sarasota County, FL?

Sarasota County, Florida is in USDA Hardiness Zone 10a. The average last spring frost is February 3 and first fall frost is December 22.

🌱

Your Sarasota County Garden Planner — Free

A 24-page printable planner built for Sarasota County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Sarasota 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.