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When to Plant Fennel in Gillespie County, TX

Gillespie County, Texas Zone 8b May

May in Gillespie County, Texas — your action list

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Gillespie County, Texas.

Avg. last frost March 19
Avg. first frost November 14
Soil temp (4") 66°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Start fennel under lights

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

Get ahead of June
  • 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.

Gillespie County, Texas is in USDA Zone 8b. The average last spring frost is March 19 and the first fall frost is November 14, giving you a growing season of approximately 240 days.

At an elevation of 3,036 feet, Gillespie County receives approximately 65.8 inches of rainfall annually with predominantly loam soil. Summer highs average 91°F, providing good warmth for Fennel during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Fennel root diseases.

Gillespie County, TX (Zone 8b) Long season
240 days
Last Spring Frost March 19
240 growing days
First Fall Frost November 14
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Gillespie County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (123 days to spare)
Start indoors: Jan 18 Transplant: Mar 22 🍅 Harvest: May 24 – Jul 5
Recommended (50%) ✓ Fits season (121 days to spare)
Start indoors: Jan 29 Transplant: Apr 2 🍅 Harvest: Jun 4 – Jul 16
Safe Start (90%) ✓ Fits season (117 days to spare)
Start indoors: Feb 18 Transplant: Apr 22 🍅 Harvest: Jun 24 – Aug 5

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 Gillespie County

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

Soil pH

Your soil pH (6.5–7.8) is more alkaline than Fennel prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.0%). 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 240-day season

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

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
1.2″/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 1.6" 0" ❄️ Dormant
Feb 2.3" 0" ❄️ Dormant
Mar 2.6" 4.3" 0" ✅ Rainfall sufficient
Apr 2.6" 6.6" 0" ✅ Rainfall sufficient
May 2.6" 9.4" 0" ✅ Rainfall sufficient
Jun 2.6" 12" 0" ✅ Rainfall sufficient
Jul 2.6" 9.3" 0" ✅ Rainfall sufficient
Aug 2.6" 6.9" 0" ✅ Rainfall sufficient
Sep 2.6" 5.2" 0" ✅ Rainfall sufficient
Oct 2.6" 4.3" 0" ✅ Rainfall sufficient
Nov 2.6" 2.5" 0.1" 💧 Light watering
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Gillespie 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 4,380 GDD Excellent fit

Fennel Planting Timeline — Gillespie County, TX

Fennel Planting Calendar

Activity When Date Range
Start Indoors January 29 Jan 29 – Feb 12
Transplant Outdoors April 2 Apr 2 – Apr 16
Direct Sow March 26 Mar 26 – Apr 16
Harvest June 4 Jun 4 – Jul 16

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 8b

📆 Growing Season

240 days in Gillespie County

Growing Tips for Fennel in Gillespie County

Direct sow Fennel outdoors after March 19 in Gillespie 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 Gillespie County, TX?

Gillespie County is in Zone 8b with an average last frost of March 19. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gillespie County, TX?

Gillespie County, Texas is in USDA Hardiness Zone 8b. The average last spring frost is March 19 and first fall frost is November 14.

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Your Gillespie County Garden Planner — Free

A 24-page printable planner built for Gillespie County (Zone 8b). 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 Gillespie County, TX. 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.