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When to Plant Fennel in Spokane County, WA

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.

Spokane County, Washington is in USDA Zone 6a. The average last spring frost is May 11 and the first fall frost is September 27, giving you a growing season of approximately 139 days.

At an elevation of 1,645 feet, Spokane County receives approximately 20.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91ยฐF, providing good warmth for Fennel during the growing season.

Spokane County, WA (Zone 6a) Short season
139 days
Last Spring Frost May 11
139 growing days
First Fall Frost September 27

Spokane County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: Mar 5 Transplant: May 14 🍅 Harvest: Jul 16 – Aug 27
Recommended (50%) ✓ Fits season (20 days to spare)
Start indoors: Mar 16 Transplant: May 25 🍅 Harvest: Jul 27 – Sep 7
Safe Start (90%) ✓ Fits season (12 days to spare)
Start indoors: Apr 17 Transplant: Jun 26 🍅 Harvest: Aug 28 – Oct 9

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
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 475 gal / 100 sq ft
Fennel needs ~1,369 GDD — county provides 2,536 GDD Excellent fit

Fennel Planting Timeline โ€” Spokane County, WA

Fennel Planting Calendar

Activity When Date Range
Start Indoors March 16 Mar 16 โ€“ Mar 30
Transplant Outdoors May 25 May 25 โ€“ Jun 8
Direct Sow May 18 May 18 โ€“ Jun 8
Harvest July 27 Jul 27 โ€“ Sep 7

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April โ€”
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
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 6a

Growing Season

139 days

Growing Tips for Spokane County

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

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Frequently Asked Questions

When should I plant Fennel in Spokane County, WA?

Spokane County is in Zone 6a with an average last frost of May 11. Plan your Fennel planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Spokane County, WA?

Spokane County, Washington is in USDA Hardiness Zone 6a. The average last spring frost is May 11 and first fall frost is September 27.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Spokane County gardeners in Zone 6a 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 Spokane County, WA. Local conditions may vary. Last updated: April 2026.