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

Freeborn County, Minnesota Zone 5a May

May to-do list for Freeborn County, Minnesota

Your garden in Freeborn County, Minnesota is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 1
Avg. first frost October 7
Soil temp (4") 55°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
Looking ahead to June
  • Starting indoors: fennel (herb)
  • First harvests: 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.

Freeborn County, Minnesota is in USDA Zone 5a. The average last spring frost is May 1 and the first fall frost is October 7, giving you a growing season of approximately 159 days.

At an elevation of 1,253 feet, Freeborn County receives approximately 34.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Fennel (herb) to ensure they mature before fall.

Freeborn County, MN (Zone 5a) Moderate season
159 days
Last Spring Frost May 1
159 growing days
First Fall Frost October 7

Freeborn County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Mar 20 Transplant: Apr 17 🍅 Harvest: Jun 19 – Aug 28
Recommended (50%) ✓ Fits season (33 days to spare)
Start indoors: Mar 27 Transplant: Apr 24 🍅 Harvest: Jun 26 – Sep 4
Safe Start (90%) ✓ Fits season (28 days to spare)
Start indoors: Apr 10 Transplant: May 8 🍅 Harvest: Jul 10 – Sep 18

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 Freeborn County

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

Soil pH

Your soil pH (5.8–7.3) overlaps with Fennel (herb)'s range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.9%) — 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)

3
successive plantings in your 159-day season

Sow every 6.9 weeks. Last sowing by Jul 09 to harvest before frost.

For a dedicated fall crop, sow by Jul 29.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 118 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 1.3" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 4.8" 0" ✅ Rainfall sufficient
Jul 4.3" 3.5" 0.8" 💧 Light watering
Aug 4.3" 3.9" 0.4" 💧 Light watering
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 4.3" 2.5" 1.8" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Freeborn 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 ~975 GDD — county provides 2,067 GDD Excellent fit

Fennel (herb) Planting Timeline — Freeborn County, MN

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors March 27 Mar 27 – Apr 10
Transplant Outdoors April 24 Apr 24 – May 8
Direct Sow April 17 Apr 17 – May 8
Harvest June 26 Jun 26 – Sep 4
Fall Sowing July 29 Jul 29 – Aug 12

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Fall Sowing 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 5a

📆 Growing Season

159 days in Freeborn County

Growing Tips for Fennel (herb) in Freeborn County

Direct sow Fennel (herb) outdoors after May 01 in Freeborn 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 Freeborn County, MN?

Freeborn County is in Zone 5a with an average last frost of May 1. Plan your Fennel (herb) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Freeborn County, MN?

Freeborn County, Minnesota is in USDA Hardiness Zone 5a. The average last spring frost is May 1 and first fall frost is October 7.

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Your Freeborn County Garden Planner — Free

A 24-page printable planner built for Freeborn County (Zone 5a). 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 Freeborn 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.