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When to plant Fennel in Bath, IL

Plant Fennel in Bath from April 22 to May 13 in spring. Bath sits in USDA Zone 6a, with last frost around April 15 and first frost on October 14.

When to Plant Fennel in Bath, IL

Mason County, Illinois Zone 6a July

Top priorities for Mason County, Illinois gardeners in July

Here's what deserves your attention in Mason County, Illinois this month. Everything below is tailored to Zone 6a and timed around your local frost dates.

Avg. last frost April 15
Avg. first frost October 14
Soil temp (4") 77°F
Watering Moderate
Pest pressure High
Daylight 14.6 hrs
  1. Harvest fennel as they ripen

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

August will be here before you know it — start on
  • First harvests: 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.

Bath, Illinois is in USDA Zone 6a. The average last spring frost is April 15 and the first fall frost is October 14, giving you a growing season of approximately 182 days.

At an elevation of 768 feet, Mason County receives approximately 30.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Fennel during the growing season.

Bath, IL (Zone 6a) Moderate season
182 days
Last Spring Frost April 15
182 growing days
First Fall Frost October 14

Bath Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Fennel Planting Risk Windows

Early Start (70% safe) ✓ Fits season (59 days to spare)
Start indoors: Feb 15 Transplant: Apr 26 🍅 Harvest: Jun 28 – Aug 9
Recommended (50%) ✓ Fits season (63 days to spare)
Start indoors: Feb 18 Transplant: Apr 29 🍅 Harvest: Jul 1 – Aug 12
Safe Start (90%) ✓ Fits season (62 days to spare)
Start indoors: Mar 5 Transplant: May 14 🍅 Harvest: Jul 16 – Aug 27

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 Bath

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

Soil pH

Your soil pH (6.1–6.9) is within Fennel's preferred range (5.5–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.8%) — Fennel will thrive.

How to Plant Fennel

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

Succession Planting Fennel

3
successive plantings in your 182-day season

Sow every 6.9 weeks. Last sowing by Jul 16 to harvest before frost.

Fennel Water Budget

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

Water stress score is 6/10 — 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 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.6" 3" 0" ✅ Rainfall sufficient
May 2.6" 3.3" 0" ✅ Rainfall sufficient
Jun 2.6" 4.1" 0" ✅ Rainfall sufficient
Jul 2.6" 3.3" 0" ✅ Rainfall sufficient
Aug 2.6" 3.4" 0" ✅ Rainfall sufficient
Sep 2.6" 2.7" 0" ✅ Rainfall sufficient
Oct 2.6" 2.2" 0.4" 💧 Light watering
Nov 2" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Mason 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 ~1,088 GDD — county provides 2,639 GDD Excellent fit

Fennel Planting Timeline — Bath, IL

Fennel Planting Calendar

Activity When Date Range
Start Indoors February 18 Feb 18 – Mar 4
Transplant Outdoors April 29 Apr 29 – May 13
Direct Sow April 22 Apr 22 – May 13
Harvest July 1 Jul 1 – Aug 12

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Harvest
August Harvest
September
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: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

182 days in Mason County

Growing Tips for Fennel in Bath

Direct sow Fennel outdoors after April 15 in Mason 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 →

When should I plant Fennel in Bath, IL?

In Bath, IL, plant Fennel after the last frost (around April 15) and before the first frost (around October 14). Best results when soil holds above 50°F.

What growing zone is Bath, IL for Fennel?

Bath sits in USDA Zone 6a. Fennel grows reliably in zones 4a through 10b, so it's a good fit here.

Can Fennel grow in Bath's climate?

Yes — Fennel grows well in Bath's temperate climate. Bath averages a 182-day frost-free season, with last frost around April 15 and first frost around October 14.

🌱

Your Mason County Garden Planner — Free

A 22-page printable planner built for Mason County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Mason County, IL. Local conditions may vary. Last updated: July 2026.