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When to Plant Fennel (herb) in Williams County, ND

Williams County, North Dakota Zone 4a April

Your April game plan for Williams County, North Dakota

We've pulled the most time-sensitive tasks for Williams County, North Dakota this April and put them front and centre. Tackle them in order.

Avg. last frost May 14
Avg. first frost September 22
Soil temp (4") 42°F
Watering Moderate
Pest pressure Low
Daylight 13.4 hrs
To set up a strong May, finish these tasks
  • Transplants going out: fennel (herb)
  • Direct-sowing: 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.

Williams County, North Dakota is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 22, giving you a growing season of approximately 131 days.

At an elevation of 947 feet, Williams County receives approximately 28.1 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Fennel (herb) to ensure they mature before fall.

Williams County, ND (Zone 4a) Short season
131 days
Last Spring Frost May 14
131 growing days
First Fall Frost September 22
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Williams County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jul 5 – Sep 13
Recommended (50%) ✓ Fits season (5 days to spare)
Start indoors: Apr 2 Transplant: May 7 🍅 Harvest: Jul 9 – Sep 17
Safe Start (90%) ✓ Fits season (2 days to spare)
Start indoors: Apr 18 Transplant: May 23 🍅 Harvest: Jul 25 – 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 Williams County

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

Soil pH

Your soil pH (6.4–7.6) overlaps with Fennel (herb)'s range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Fennel (herb).

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 131-day season

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

For a dedicated fall crop, sow by Jun 30.

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 139 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 1.5" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 2.1" 2.2" 🚿 Regular watering
Jul 4.3" 2.4" 1.9" 💧 Light watering
Aug 4.3" 2.5" 1.8" 💧 Light watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 2.7" 0" ❄️ Dormant
Nov 2.2" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Williams 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 1,703 GDD Excellent fit

Fennel (herb) Planting Timeline — Williams County, ND

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors May 7 May 7 – May 21
Direct Sow May 7 May 7 – May 28
Harvest July 9 Jul 9 – Sep 17
Fall Sowing June 30 Jun 30 – Jul 14

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 Fall Sowing
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 · 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

131 days in Williams County

Growing Tips for Fennel (herb) in Williams County

Direct sow Fennel (herb) outdoors after May 14 in Williams 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 Williams County, ND?

Williams County is in Zone 4a with an average last frost of May 14. Plan your Fennel (herb) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Williams County, ND?

Williams County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 22.

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Your Williams County Garden Planner — Free

A 24-page printable planner built for Williams 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 Williams County, ND. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.