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When to Plant Fennel in Pembina County, ND

Pembina County, North Dakota Zone 4a May

Top priorities for Pembina County, North Dakota gardeners in May

Welcome to May in Zone 4a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 15
Avg. first frost September 28
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 15 hrs
  1. Scatter fennel into prepared beds

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

June prep starts now
  • Transplants going out: 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.

Pembina County, North Dakota is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 28, giving you a growing season of approximately 136 days.

At an elevation of 958 feet, Pembina County receives approximately 26.5 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Fennel to ensure they mature before fall.

Pembina County, ND (Zone 4a) Short season
136 days
Last Spring Frost May 15
136 growing days
First Fall Frost September 28

Pembina County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Mar 9 Transplant: Jun 1 🍅 Harvest: Aug 3 – Sep 14
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: Mar 13 Transplant: Jun 5 🍅 Harvest: Aug 7 – Sep 18
Safe Start (90%) ✓ Fits season (9 days to spare)
Start indoors: Mar 28 Transplant: Jun 20 🍅 Harvest: Aug 22 – Oct 3

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 Pembina County

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

Soil pH

Your soil pH (6.6–7.3) overlaps with Fennel's range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) — Fennel will thrive.

How to Plant Fennel

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

Succession Planting Fennel

2
successive plantings in your 136-day season

Sow every 6.9 weeks. Last sowing by Jun 30 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 0.7" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 2.6" 3.6" 0" ✅ Rainfall sufficient
Jun 2.6" 4.7" 0" ✅ Rainfall sufficient
Jul 2.6" 3.2" 0" ✅ Rainfall sufficient
Aug 2.6" 3.4" 0" ✅ Rainfall sufficient
Sep 2.6" 2.7" 0" ✅ Rainfall sufficient
Oct 1.4" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Pembina 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 ~694 GDD — county provides 1,258 GDD Excellent fit

Fennel Planting Timeline — Pembina County, ND

Fennel Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors June 5 Jun 5 – Jun 19
Direct Sow May 29 May 29 – Jun 19
Harvest August 7 Aug 7 – Sep 18

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

136 days in Pembina County

Growing Tips for Fennel in Pembina County

Direct sow Fennel outdoors after May 15 in Pembina 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 Pembina County, ND?

Pembina County is in Zone 4a with an average last frost of May 15. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pembina County, ND?

Pembina County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 28.

🌱

Your Pembina County Garden Planner — Free

A 24-page printable planner built for Pembina 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 Pembina County, ND. 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.