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When to Plant Fennel (herb) in Martin County, FL

Herb fennel is grown for its aromatic leaves, stalks, and seeds rather than a bulb. It has a strong anise flavor and its flowers attract beneficial insects.

Martin County, Florida is in USDA Zone 10a. The average last spring frost is January 25 and the first fall frost is December 13, giving you a growing season of approximately 322 days.

At an elevation of 80 feet, Martin County receives approximately 56.3 inches of rainfall annually with predominantly sand soil. Summer highs average 88ยฐF, providing good warmth for Fennel (herb) during the growing season. Sandy soil warms quickly in spring โ€” great for early planting โ€” but Fennel (herb) will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Fennel (herb) root diseases.

Martin County, FL (Zone 10a) Year-round
322 days
Last Spring Frost January 25
322 growing days
First Fall Frost December 13

Martin County Soil Profile

Soil Type

Sand

Soil pH

5.1-5.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (202 days to spare)
Start indoors: Dec 18 Transplant: Jan 8 🍅 Harvest: Mar 12 – May 21
Recommended (50%) ✓ Fits season (196 days to spare)
Start indoors: Dec 28 Transplant: Jan 18 🍅 Harvest: Mar 22 – May 31
Safe Start (90%) ✓ Fits season (183 days to spare)
Start indoors: Jan 20 Transplant: Feb 10 🍅 Harvest: Apr 14 – 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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,959 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Fennel (herb) needs ~1,200 GDD — county provides 5,168 GDD Excellent fit

Fennel (herb) Planting Timeline โ€” Martin County, FL

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors December 28 Dec 28 โ€“ Jan 11
Transplant Outdoors January 18 Jan 18 โ€“ Feb 1
Direct Sow January 4 Jan 4 โ€“ Jan 25
Fall Sowing October 18 Oct 18 โ€“ Nov 1
Harvest March 22 Mar 22 โ€“ May 31

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

Month-by-Month Timeline

MonthActivities
January Start Indoors Transplant Outdoors Direct Sow
February Transplant Outdoors
March Harvest
April Harvest
May Harvest
June โ€”
July โ€”
August โ€”
September โ€”
October Fall Sowing
November Fall Sowing
December Start Indoors

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 10a

Growing Season

322 days

Growing Tips for Martin County

Direct sow in spring or fall. Unlike Florence fennel, herb fennel does not form a bulb. Harvest fronds as needed and seeds when they turn brown. Self-sows readily.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Peppers
  • Green Beans

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Frequently Asked Questions

When should I plant Fennel (herb) in Martin County, FL?

Martin County is in Zone 10a with an average last frost of January 25. Plan your Fennel (herb) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Martin County, FL?

Martin County, Florida is in USDA Hardiness Zone 10a. The average last spring frost is January 25 and first fall frost is December 13.

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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 Martin County, FL. Local conditions may vary. Last updated: April 2026.