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When to Plant Fennel (herb) in Wallowa County, OR

Wallowa County, Oregon Zone 6b May

Your May planting checklist for Wallowa County, Oregon

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

Avg. last frost May 11
Avg. first frost September 22
Soil temp (4") 57°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
  1. Time to transplant fennel (herb)

    Frost risk is low now in Wallowa County, Oregon. If you've been covering beds overnight, you can stop.

June will be here before you know it — start on
  • Starting indoors: fennel (herb)

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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.

Wallowa County, Oregon is in USDA Zone 6b. The average last spring frost is May 11 and the first fall frost is September 22, giving you a growing season of approximately 134 days.

At an elevation of 1,240 feet, Wallowa County receives approximately 22.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Fennel (herb) during the growing season.

Wallowa County, OR (Zone 6b) Short season
134 days
Last Spring Frost May 11
134 growing days
First Fall Frost September 22
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Wallowa County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (6 days to spare)
Start indoors: Mar 27 Transplant: Apr 24 🍅 Harvest: Jun 26 – Sep 4
Recommended (50%) ✓ Fits season (8 days to spare)
Start indoors: Apr 6 Transplant: May 4 🍅 Harvest: Jul 6 – Sep 14
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: May 8 Transplant: Jun 5 🍅 Harvest: Aug 7 – Oct 16

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 Wallowa County

How your county's soil matches Fennel (herb)'s growing requirements.

Soil pH

Your soil pH (5.3–6.2) overlaps with Fennel (herb)'s range (5.5–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Fennel (herb).

Organic Matter

Organic matter is excellent (5.4%) — Fennel (herb) will thrive.

How to Plant Fennel (herb)

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Fennel (herb)

2
successive plantings in your 134-day season

Sow every 6.9 weeks. Last sowing by Jun 24 to harvest before frost.

For a dedicated fall crop, sow by Jul 14.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 706 gal / 100 sq ft

Monthly Watering Guide for Fennel (herb)

Fennel (herb) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Fennel (herb) Needs Rainfall You Supplement Action
Jan 2.9" 0" ❄️ Dormant
Feb 2.3" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 1.5" 0" ❄️ Dormant
May 4.3" 1.3" 3" 🚿 Regular watering
Jun 4.3" 1" 3.3" 🚿 Regular watering
Jul 4.3" 0.4" 3.9" 🚿 Regular watering
Aug 4.3" 0.4" 3.9" 🚿 Regular watering
Sep 4.3" 1" 3.3" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 3.9" 0" ❄️ Dormant
Dec 3.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Wallowa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Fennel (herb) 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 (herb) needs ~1,031 GDD — county provides 1,842 GDD Excellent fit

Fennel (herb) Planting Timeline — Wallowa County, OR

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors April 6 Apr 6 – Apr 20
Transplant Outdoors May 4 May 4 – May 18
Direct Sow April 27 Apr 27 – May 18
Harvest July 6 Jul 6 – Sep 14
Fall Sowing July 14 Jul 14 – Jul 28

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

134 days in Wallowa County

Growing Tips for Fennel (herb) in Wallowa County

Direct sow Fennel (herb) outdoors after May 11 in Wallowa County when soil has warmed and frost danger has passed.

Common pests for Fennel (herb) in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

Wallowa County receives only 23" of rain annually. Fennel (herb) needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Fennel (herb) in Wallowa County, OR?

Wallowa County is in Zone 6b with an average last frost of May 11. Plan your Fennel (herb) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Wallowa County, OR?

Wallowa County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is May 11 and first fall frost is September 22.

🌱

Your Wallowa County Garden Planner — Free

A 24-page printable planner built for Wallowa County (Zone 6b). 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 Wallowa County, OR. 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.