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When to Plant Fennel in Sioux County, NE

Sioux County, Nebraska Zone 5a May

May to-do list for Sioux County, Nebraska

Here's what deserves your attention in Sioux County, Nebraska this month. Everything below is tailored to Zone 5a and timed around your local frost dates.

Avg. last frost May 16
Avg. first frost September 22
Soil temp (4") 53°F
Watering High
Pest pressure Low
Daylight 14.4 hrs
  1. Time to transplant fennel

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Direct-sow fennel

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

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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.

Sioux County, Nebraska is in USDA Zone 5a. The average last spring frost is May 16 and the first fall frost is September 22, giving you a growing season of approximately 129 days.

At an elevation of 775 feet, Sioux County receives approximately 24.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Fennel to ensure they mature before fall.

Sioux County, NE (Zone 5a) Short season
129 days
Last Spring Frost May 16
129 growing days
First Fall Frost September 22
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Sioux County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (7 days to spare)
Start indoors: Mar 16 Transplant: May 25 🍅 Harvest: Jul 27 – Sep 7
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: Mar 21 Transplant: May 30 🍅 Harvest: Aug 1 – Sep 12
Safe Start (90%) ✓ Fits season (2 days to spare)
Start indoors: Apr 14 Transplant: Jun 23 🍅 Harvest: Aug 25 – 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 Sioux County

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

Soil pH

Your soil pH (6.3–7.2) overlaps with Fennel's range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.3%) — Fennel will thrive.

How to Plant Fennel

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

Succession Planting Fennel

2
successive plantings in your 129-day season

Sow every 6.9 weeks. Last sowing by Jun 24 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
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

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 1.7" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 2.5" 0" ❄️ Dormant
May 2.6" 2.7" 0" ✅ Rainfall sufficient
Jun 2.6" 1.6" 1" 💧 Light watering
Jul 2.6" 2" 0.6" 💧 Light watering
Aug 2.6" 2.8" 0" ✅ Rainfall sufficient
Sep 2.6" 2.2" 0.4" 💧 Light watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Sioux 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 ~975 GDD — county provides 1,677 GDD Excellent fit

Fennel Planting Timeline — Sioux County, NE

Fennel Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 – Apr 4
Transplant Outdoors May 30 May 30 – Jun 13
Direct Sow May 23 May 23 – Jun 13
Harvest August 1 Aug 1 – Sep 12

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July
August Harvest
September Harvest
October
November
December
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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 5a

📆 Growing Season

129 days in Sioux County

Growing Tips for Fennel in Sioux County

Direct sow Fennel outdoors after May 16 in Sioux 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 Sioux County, NE?

Sioux County is in Zone 5a with an average last frost of May 16. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sioux County, NE?

Sioux County, Nebraska is in USDA Hardiness Zone 5a. The average last spring frost is May 16 and first fall frost is September 22.

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Your Sioux County Garden Planner — Free

A 24-page printable planner built for Sioux 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 Sioux County, NE. 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.