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When to Plant Fennel in Caldwell County, TX

Caldwell County, Texas Zone 9a May

This month in Caldwell County, Texas

May is a pivotal month for Caldwell County, Texas gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost February 27
Avg. first frost December 1
Soil temp (4") 66°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Start harvesting fennel

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

To set up a strong June, finish these tasks
  • 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.

Caldwell County, Texas is in USDA Zone 9a. The average last spring frost is February 27 and the first fall frost is December 1, giving you a growing season of approximately 277 days.

At an elevation of 3,482 feet, Caldwell County receives approximately 60.8 inches of rainfall annually with predominantly clay soil. Summer highs average 90°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.

Caldwell County, TX (Zone 9a) Year-round
277 days
Last Spring Frost February 27
277 growing days
First Fall Frost December 1
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Caldwell County Soil Profile

Soil Type

Clay

Soil pH

6.8-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (167 days to spare)
Start indoors: Jan 2 Transplant: Feb 20 🍅 Harvest: Apr 24 – Jun 5
Recommended (50%) ✓ Fits season (165 days to spare)
Start indoors: Jan 16 Transplant: Mar 6 🍅 Harvest: May 8 – Jun 19
Safe Start (90%) ✓ Fits season (154 days to spare)
Start indoors: Feb 8 Transplant: Mar 29 🍅 Harvest: May 31 – Jul 12

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 Caldwell County

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

Soil pH

Your soil pH (6.8–8.1) is more alkaline than Fennel prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Heavy clay soil (43% clay) in Caldwell County compacts easily and drains slowly. Amend with compost and avoid working soil when wet.

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Fennel.

How to Plant Fennel

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

Succession Planting Fennel

5
successive plantings in your 277-day season

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

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.9″/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 1.4" 0" ❄️ Dormant
Feb 2.6" 2.1" 0.5" 💧 Light watering
Mar 2.6" 4.1" 0" ✅ Rainfall sufficient
Apr 2.6" 6" 0" ✅ Rainfall sufficient
May 2.6" 9.9" 0" ✅ Rainfall sufficient
Jun 2.6" 9.2" 0" ✅ Rainfall sufficient
Jul 2.6" 7.5" 0" ✅ Rainfall sufficient
Aug 2.6" 7.9" 0" ✅ Rainfall sufficient
Sep 2.6" 5.6" 0" ✅ Rainfall sufficient
Oct 2.6" 3.8" 0" ✅ Rainfall sufficient
Nov 2.6" 1.8" 0.8" 💧 Light watering
Dec 2.6" 1.5" 1.1" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in Caldwell 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 ~1,312 GDD — county provides 4,865 GDD Excellent fit

Fennel Planting Timeline — Caldwell County, TX

Fennel Planting Calendar

Activity When Date Range
Start Indoors January 16 Jan 16 – Jan 30
Transplant Outdoors March 6 Mar 6 – Mar 20
Direct Sow February 27 Feb 27 – Mar 20
Harvest May 8 May 8 – Jun 19

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

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Direct Sow
March Transplant Outdoors Direct Sow
April
May Harvest
June Harvest
July
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 9a

📆 Growing Season

277 days in Caldwell County

Growing Tips for Fennel in Caldwell County

Direct sow Fennel outdoors after February 27 in Caldwell County when soil has warmed and frost danger has passed.

With Caldwell County's clay soil (43% 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 Caldwell County, TX?

Caldwell County is in Zone 9a with an average last frost of February 27. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.

What planting zone is Caldwell County, TX?

Caldwell County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 27 and first fall frost is December 1.

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Your Caldwell County Garden Planner — Free

A 24-page printable planner built for Caldwell County (Zone 9a). 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 Caldwell 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.