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When to Plant Fennel in Seminole County, FL

Seminole County, Florida Zone 10a May

Your May game plan for Seminole County, Florida

We've pulled the most time-sensitive tasks for Seminole County, Florida this May and put them front and centre. Tackle them in order.

Avg. last frost February 3
Avg. first frost December 21
Soil temp (4") 78°F
Watering Low
Pest pressure High
Daylight 13.4 hrs
  1. Harvest fennel as they ripen

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

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Florence fennel is grown for its swollen bulb-like stem base, which has a mild anise flavor. It is crisp raw in salads and sweet when roasted or braised.

Seminole County, Florida is in USDA Zone 10a. The average last spring frost is February 3 and the first fall frost is December 21, giving you a growing season of approximately 321 days.

At an elevation of 260 feet, Seminole County receives approximately 53.9 inches of rainfall annually with predominantly sand soil. Summer highs average 95°F, so Fennel may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Fennel will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Fennel root diseases.

Seminole County, FL (Zone 10a) Year-round
321 days
Last Spring Frost February 3
321 growing days
First Fall Frost December 21
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Seminole County Soil Profile

Soil Type

Sand

Soil pH

5.2-5.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (220 days to spare)
Start indoors: Dec 8 Transplant: Jan 26 🍅 Harvest: Mar 30 – May 11
Recommended (50%) ✓ Fits season (209 days to spare)
Start indoors: Dec 23 Transplant: Feb 10 🍅 Harvest: Apr 14 – May 26
Safe Start (90%) ✓ Fits season (186 days to spare)
Start indoors: Jan 20 Transplant: Mar 10 🍅 Harvest: May 12 – Jun 23

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 Seminole County

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

Soil pH

Your soil pH (5.2–5.9) overlaps with Fennel's range (5.5–7.0), though not a perfect match.

Soil Texture

Sandy soil in Seminole County warms quickly in spring but drains fast. Fennel will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Fennel.

Organic Matter

Organic matter is low (1.5%). Add 2-3 inches of compost before planting Fennel.

How to Plant Fennel

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Succession Planting Fennel

6
successive plantings in your 321-day season

Sow every 6.9 weeks. Last sowing by Sep 22 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.7″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 265 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Fennel

Fennel needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Fennel Needs Rainfall You Supplement Action
Jan 2.9" 0" ❄️ Dormant
Feb 2.6" 3" 0" ✅ Rainfall sufficient
Mar 2.6" 2.9" 0" ✅ Rainfall sufficient
Apr 2.6" 2.8" 0" ✅ Rainfall sufficient
May 2.6" 3.8" 0" ✅ Rainfall sufficient
Jun 2.6" 7.9" 0" ✅ Rainfall sufficient
Jul 2.6" 7.7" 0" ✅ Rainfall sufficient
Aug 2.6" 6.9" 0" ✅ Rainfall sufficient
Sep 2.6" 6.4" 0" ✅ Rainfall sufficient
Oct 2.6" 5.2" 0" ✅ Rainfall sufficient
Nov 2.6" 2.2" 0.4" 💧 Light watering
Dec 2.6" 2.2" 0.4" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in Seminole County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Fennel 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.

Fennel needs ~1,594 GDD — county provides 6,842 GDD Excellent fit

Fennel Planting Timeline — Seminole County, FL

Fennel Planting Calendar

Activity When Date Range
Start Indoors December 23 Dec 23 – Jan 6
Transplant Outdoors February 10 Feb 10 – Feb 24
Direct Sow February 3 Feb 3 – Feb 24
Harvest April 14 Apr 14 – May 26

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Transplant Outdoors Direct Sow
March
April Harvest
May Harvest
June
July
August
September
October
November
December Start Indoors
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

321 days in Seminole County

Growing Tips for Fennel in Seminole County

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

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

Common pests for Fennel in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in late summer for fall harvest to reduce bolting. Hill soil around bulbs as they enlarge. Harvest when bulbs are tennis-ball sized before they elongate.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Peppers
  • Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Fennel in Seminole County, FL?

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

What planting zone is Seminole County, FL?

Seminole County, Florida is in USDA Hardiness Zone 10a. The average last spring frost is February 3 and first fall frost is December 21.

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Your Seminole County Garden Planner — Free

A 24-page printable planner built for Seminole 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.

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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 Seminole 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.