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When to Plant Fennel (herb) in Wadena County, MN

Wadena County, Minnesota Zone 4a May

May in Wadena County, Minnesota — your action list

May is a pivotal month for Wadena County, Minnesota gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 13
Avg. first frost September 27
Soil temp (4") 49°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Get fennel (herb) in the ground

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Outdoor sowing time: fennel (herb)

    These tolerate cool soil, so you're not gambling by sowing now.

Looking ahead to June
  • 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.

Wadena County, Minnesota is in USDA Zone 4a. The average last spring frost is May 13 and the first fall frost is September 27, giving you a growing season of approximately 137 days.

At an elevation of 1,320 feet, Wadena County receives approximately 40.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Fennel (herb) to ensure they mature before fall.

Wadena County, MN (Zone 4a) Short season
137 days
Last Spring Frost May 13
137 growing days
First Fall Frost September 27

Wadena County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Mar 23 Transplant: Apr 27 🍅 Harvest: Jun 29 – Sep 7
Recommended (50%) ✓ Fits season (11 days to spare)
Start indoors: Apr 1 Transplant: May 6 🍅 Harvest: Jul 8 – Sep 16
Safe Start (90%) ✓ Fits season (14 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Jul 17 – Sep 25

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 Wadena County

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

Soil pH

Your soil pH (6.1–7.3) overlaps with Fennel (herb)'s range (5.5–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Wadena 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 (4.8%) — Fennel (herb) will thrive.

How to Plant Fennel (herb)

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Fennel (herb)

2
successive plantings in your 137-day season

Sow every 6.9 weeks. Last sowing by Jun 29 to harvest before frost.

For a dedicated fall crop, sow by Jul 05.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 103 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.8" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 3.3" 0" ❄️ Dormant
Apr 3.7" 0" ❄️ Dormant
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 4.8" 0" ✅ Rainfall sufficient
Jul 4.3" 4.5" 0" ✅ Rainfall sufficient
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 3.9" 0.4" 💧 Light watering
Oct 2.8" 0" ❄️ Dormant
Nov 2.6" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Wadena 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 ~694 GDD — county provides 1,267 GDD Excellent fit

Fennel (herb) Planting Timeline — Wadena County, MN

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 6 May 6 – May 20
Direct Sow May 6 May 6 – May 27
Harvest July 8 Jul 8 – Sep 16
Fall Sowing July 5 Jul 5 – Jul 19

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

137 days in Wadena County

Growing Tips for Fennel (herb) in Wadena County

Direct sow Fennel (herb) outdoors after May 13 in Wadena 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.

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 Wadena County, MN?

Wadena County is in Zone 4a with an average last frost of May 13. Plan your Fennel (herb) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Wadena County, MN?

Wadena County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 13 and first fall frost is September 27.

🌱

Your Wadena County Garden Planner — Free

A 24-page printable planner built for Wadena County (Zone 4a). 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 Wadena County, MN. 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.