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When to Plant Fennel in Union County, SC

Union County, South Carolina Zone 7b April

Your April game plan for Union County, South Carolina

Your Union County, South Carolina garden is entering a new phase. Here's what's on the schedule for April and why each task matters now.

Avg. last frost April 5
Avg. first frost October 31
Soil temp (4") 59°F
Watering Low
Pest pressure Moderate
Daylight 12.9 hrs
  1. Move fennel from tray to bed

    Frost risk is low now in Union County, South Carolina. If you've been covering beds overnight, you can stop.

  2. Outdoor sowing time: fennel

    Your soil is 59°F — warm enough for these to germinate without babying.

To set up a strong May, finish these tasks
  • Starting indoors: 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.

Union County, South Carolina is in USDA Zone 7b. The average last spring frost is April 5 and the first fall frost is October 31, giving you a growing season of approximately 209 days.

At an elevation of 478 feet, Union County receives approximately 53.3 inches of rainfall annually with predominantly clay loam soil. Summer highs average 91°F, providing good warmth for Fennel during the growing season. Clay soil retains moisture well for Fennel, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Fennel root diseases.

Union County, SC (Zone 7b) Long season
209 days
Last Spring Frost April 5
209 growing days
First Fall Frost October 31
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Union County Soil Profile

Soil Type

Clay Loam

Soil pH

5.7-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (93 days to spare)
Start indoors: Feb 6 Transplant: Apr 10 🍅 Harvest: Jun 12 – Jul 24
Recommended (50%) ✓ Fits season (90 days to spare)
Start indoors: Feb 15 Transplant: Apr 19 🍅 Harvest: Jun 21 – Aug 2
Safe Start (90%) ✓ Fits season (98 days to spare)
Start indoors: Feb 28 Transplant: May 2 🍅 Harvest: Jul 4 – Aug 15

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 Union County

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

Soil pH

Your soil pH (5.7–6.3) is within Fennel's preferred range (5.5–7.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Fennel.

How to Plant Fennel

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

Succession Planting Fennel

4
successive plantings in your 209-day season

Sow every 6.9 weeks. Last sowing by Aug 02 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
1.1″/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 5.1" 0" ❄️ Dormant
Feb 3.9" 0" ❄️ Dormant
Mar 4.5" 0" ❄️ Dormant
Apr 2.6" 4.5" 0" ✅ Rainfall sufficient
May 2.6" 3.8" 0" ✅ Rainfall sufficient
Jun 2.6" 5.2" 0" ✅ Rainfall sufficient
Jul 2.6" 5.5" 0" ✅ Rainfall sufficient
Aug 2.6" 4.5" 0" ✅ Rainfall sufficient
Sep 2.6" 4" 0" ✅ Rainfall sufficient
Oct 2.6" 3.5" 0" ✅ Rainfall sufficient
Nov 4.1" 0" ❄️ Dormant
Dec 4.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Union 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 ~1,369 GDD — county provides 3,814 GDD Excellent fit

Fennel Planting Timeline — Union County, SC

Fennel Planting Calendar

Activity When Date Range
Start Indoors February 15 Feb 15 – Mar 1
Transplant Outdoors April 19 Apr 19 – May 3
Direct Sow April 12 Apr 12 – May 3
Harvest June 21 Jun 21 – Aug 2

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 Harvest
July Harvest
August Harvest
September
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: ideal

🗺️ USDA Zone

Zone 7b

📆 Growing Season

209 days in Union County

Growing Tips for Fennel in Union County

Direct sow Fennel outdoors after April 05 in Union County when soil has warmed and frost danger has passed.

With Union County's clay soil (27% clay), work in 3-4 inches of compost before planting Fennel. Avoid tilling when soil is wet to prevent compaction.

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 Union County, SC?

Union County is in Zone 7b with an average last frost of April 5. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.

What planting zone is Union County, SC?

Union County, South Carolina is in USDA Hardiness Zone 7b. The average last spring frost is April 5 and first fall frost is October 31.

🌱

Your Union County Garden Planner — Free

A 24-page printable planner built for Union County (Zone 7b). 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 Union County, SC. 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.