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When to Plant Fennel in Douglas County, WA

Douglas County, Washington Zone 7a May

This month in Douglas County, Washington

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Douglas County, Washington.

Avg. last frost May 8
Avg. first frost October 4
Soil temp (4") 54°F
Watering Critical
Pest pressure Low
Daylight 14.9 hrs
  1. Plant out fennel

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

  2. Seed fennel outdoors

    Your soil is 54°F — warm enough for these to germinate without babying.

Coming up in June — start thinking about
  • Starting indoors: fennel

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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.

Douglas County, Washington is in USDA Zone 7a. The average last spring frost is May 8 and the first fall frost is October 4, giving you a growing season of approximately 149 days.

At an elevation of 2,920 feet, Douglas County receives approximately 15.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Fennel during the growing season. With low rainfall, drip irrigation is essential for growing Fennel successfully. Mulch heavily to conserve soil moisture.

Douglas County, WA (Zone 7a) Short season
149 days
Last Spring Frost May 8
149 growing days
First Fall Frost October 4

Douglas 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 (41 days to spare)
Start indoors: Mar 1 Transplant: May 3 🍅 Harvest: Jul 5 – Aug 16
Recommended (50%) ✓ Fits season (30 days to spare)
Start indoors: Mar 20 Transplant: May 22 🍅 Harvest: Jul 24 – Sep 4
Safe Start (90%) ✓ Fits season (27 days to spare)
Start indoors: Apr 22 Transplant: Jun 24 🍅 Harvest: Aug 26 – Oct 7

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 Douglas County

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

Soil pH

Your soil pH (5.5–6.2) is within Fennel's preferred range (5.5–7.0).

Soil Texture

The silt loam soil in Douglas County is excellent for Fennel — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (5.5%) — Fennel will thrive.

How to Plant Fennel

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

Succession Planting Fennel

2
successive plantings in your 149-day season

Sow every 6.9 weeks. Last sowing by Jul 06 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.5″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 246 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 2.2" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.2" 0" ❄️ Dormant
May 2.6" 0.8" 1.8" 🚿 Regular watering
Jun 2.6" 0.6" 2" 🚿 Regular watering
Jul 2.6" 0.2" 2.4" 🚿 Regular watering
Aug 2.6" 0.3" 2.3" 🚿 Regular watering
Sep 2.6" 0.7" 1.9" 🚿 Regular watering
Oct 2.6" 1.2" 1.4" 🚿 Regular watering
Nov 2.5" 0" ❄️ Dormant
Dec 2.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Douglas 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 ~1,312 GDD — county provides 2,607 GDD Excellent fit

Fennel Planting Timeline — Douglas County, WA

Fennel Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 – Apr 3
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 15 May 15 – Jun 5
Harvest July 24 Jul 24 – Sep 4

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

Month-by-Month Timeline

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

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: ideal

🗺️ USDA Zone

Zone 7a

📆 Growing Season

149 days in Douglas County

Growing Tips for Fennel in Douglas County

Direct sow Fennel outdoors after May 08 in Douglas County when soil has warmed and frost danger has passed.

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 Douglas County, WA?

Douglas County is in Zone 7a with an average last frost of May 8. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.

What planting zone is Douglas County, WA?

Douglas County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is May 8 and first fall frost is October 4.

🌱

Your Douglas County Garden Planner — Free

A 24-page printable planner built for Douglas County (Zone 7a). 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 Douglas County, WA. 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.