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When to Plant Fennel (herb) in Washington County, UT

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.

Washington County, Utah is in USDA Zone 8a. The average last spring frost is April 6 and the first fall frost is November 1, giving you a growing season of approximately 209 days.

At an elevation of 3,524 feet, Washington County receives approximately 12.7 inches of rainfall annually with predominantly loam soil. Summer highs average 90ยฐF, providing good warmth for Fennel (herb) during the growing season. With low rainfall, drip irrigation is essential for growing Fennel (herb) successfully. Mulch heavily to conserve soil moisture.

Washington County, UT (Zone 8a) Long season
209 days
Last Spring Frost April 6
209 growing days
First Fall Frost November 1

Washington County Soil Profile

Soil Type

Loam

Soil pH

6.7-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (91 days to spare)
Start indoors: Feb 6 Transplant: Mar 6 🍅 Harvest: May 8 – Jul 17
Recommended (50%) ✓ Fits season (83 days to spare)
Start indoors: Mar 2 Transplant: Mar 30 🍅 Harvest: Jun 1 – Aug 10
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Apr 22 Transplant: May 20 🍅 Harvest: Jul 22 – Sep 30

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
0.3″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 2,332 gal / 100 sq ft
Drought risk

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

Fennel (herb) needs ~1,312 GDD — county provides 3,657 GDD Excellent fit

Fennel (herb) Planting Timeline โ€” Washington County, UT

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors March 2 Mar 2 โ€“ Mar 16
Transplant Outdoors March 30 Mar 30 โ€“ Apr 13
Direct Sow March 23 Mar 23 โ€“ Apr 13
Fall Sowing August 23 Aug 23 โ€“ Sep 6
Harvest June 1 Jun 1 โ€“ Aug 10

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

Month-by-Month Timeline

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

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 8a

Growing Season

209 days

Growing Tips for Washington 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 Washington County, UT?

Washington County is in Zone 8a with an average last frost of April 6. Plan your Fennel (herb) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Washington County, UT?

Washington County, Utah is in USDA Hardiness Zone 8a. The average last spring frost is April 6 and first fall frost is November 1.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Washington County gardeners in Zone 8a organize planting dates, track what's growing, and never miss a planting window.

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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 Washington County, UT. Local conditions may vary. Last updated: April 2026.