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When to Plant Fennel in Cowlitz 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.

Cowlitz County, Washington is in USDA Zone 8a. The average last spring frost is April 15 and the first fall frost is October 29, giving you a growing season of approximately 197 days.

At an elevation of 268 feet, Cowlitz County receives approximately 47.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Fennel during the growing season.

Cowlitz County, WA (Zone 8a) Moderate season
197 days
Last Spring Frost April 15
197 growing days
First Fall Frost October 29

Cowlitz County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (75 days to spare)
Start indoors: Feb 19 Transplant: Apr 23 🍅 Harvest: Jun 25 – Aug 6
Recommended (50%) ✓ Fits season (78 days to spare)
Start indoors: Feb 25 Transplant: Apr 29 🍅 Harvest: Jul 1 – Aug 12
Safe Start (90%) ✓ Fits season (82 days to spare)
Start indoors: Mar 19 Transplant: May 21 🍅 Harvest: Jul 23 – Sep 3

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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Fennel needs ~1,144 GDD — county provides 3,004 GDD Excellent fit

Fennel Planting Timeline โ€” Cowlitz County, WA

Fennel Planting Calendar

Activity When Date Range
Start Indoors February 25 Feb 25 โ€“ Mar 11
Transplant Outdoors April 29 Apr 29 โ€“ May 13
Direct Sow April 22 Apr 22 โ€“ May 13
Harvest July 1 Jul 1 โ€“ Aug 12

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

Month-by-Month Timeline

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

197 days

Growing Tips for Cowlitz 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 Cowlitz County, WA?

Cowlitz County is in Zone 8a with an average last frost of April 15. Plan your Fennel planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Cowlitz County, WA?

Cowlitz County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 15 and first fall frost is October 29.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Cowlitz 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 Cowlitz County, WA. Local conditions may vary. Last updated: April 2026.