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When to Plant Fennel (herb) in Houghton County, MI

Houghton County, Michigan Zone 5b May

Top priorities for Houghton County, Michigan gardeners in May

Welcome to May in Zone 5b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 19
Avg. first frost October 2
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.9 hrs
  1. Harden off and plant fennel (herb)

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Scatter fennel (herb) into prepared beds

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

A few tasks this May that'll pay off in 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.

Houghton County, Michigan is in USDA Zone 5b. The average last spring frost is May 19 and the first fall frost is October 2, giving you a growing season of approximately 136 days.

At an elevation of 956 feet, Houghton County receives approximately 34.5 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.

Houghton County, MI (Zone 5b) Short season
136 days
Last Spring Frost May 19
136 growing days
First Fall Frost October 2

Houghton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (10 days to spare)
Start indoors: Apr 10 Transplant: May 8 🍅 Harvest: Jul 10 – Sep 18
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: Apr 14 Transplant: May 12 🍅 Harvest: Jul 14 – Sep 22
Safe Start (90%) ✓ Fits season (14 days to spare)
Start indoors: Apr 28 Transplant: May 26 🍅 Harvest: Jul 28 – Oct 6

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 Houghton County

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

Soil pH

Your soil pH (5.9–7.2) overlaps with Fennel (herb)'s range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Fennel (herb).

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 136-day season

Sow every 6.9 weeks. Last sowing by Jul 04 to harvest before frost.

For a dedicated fall crop, sow by Jul 24.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 2.6" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 4.2" 0.1" 💧 Light watering
Jul 4.3" 3.3" 1" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 3.4" 0.9" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.1" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Houghton 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 1,768 GDD Excellent fit

Fennel (herb) Planting Timeline — Houghton County, MI

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors April 14 Apr 14 – Apr 28
Transplant Outdoors May 12 May 12 – May 26
Direct Sow May 5 May 5 – May 26
Harvest July 14 Jul 14 – Sep 22
Fall Sowing July 24 Jul 24 – Aug 7

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 Fall Sowing Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

136 days in Houghton County

Growing Tips for Fennel (herb) in Houghton County

Direct sow Fennel (herb) outdoors after May 19 in Houghton 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 Houghton County, MI?

Houghton County is in Zone 5b with an average last frost of May 19. Plan your Fennel (herb) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Houghton County, MI?

Houghton County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 19 and first fall frost is October 2.

🌱

Your Houghton County Garden Planner — Free

A 24-page printable planner built for Houghton County (Zone 5b). 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 Houghton County, MI. 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.