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When to Plant Fennel (herb) in San Patricio County, TX

San Patricio County, Texas Zone 9b May

San Patricio County, Texas gardeners: here's your May plan

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost February 12
Avg. first frost December 9
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 13.4 hrs
  1. Pick fennel (herb)

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

June prep starts now
  • First harvests: fennel (herb)

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Herb fennel is grown for its aromatic leaves, stalks, and seeds rather than a bulb. It has a strong anise flavor and its flowers attract beneficial insects.

San Patricio County, Texas is in USDA Zone 9b. The average last spring frost is February 12 and the first fall frost is December 9, giving you a growing season of approximately 300 days.

At an elevation of 2,449 feet, San Patricio County receives approximately 54.7 inches of rainfall annually with predominantly loam soil. Summer highs average 100°F, so Fennel (herb) may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Fennel (herb) root diseases.

San Patricio County, TX (Zone 9b) Year-round
300 days
Last Spring Frost February 12
300 growing days
First Fall Frost December 9

San Patricio County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (189 days to spare)
Start indoors: Dec 23 Transplant: Jan 13 🍅 Harvest: Mar 17 – May 26
Recommended (50%) ✓ Fits season (174 days to spare)
Start indoors: Jan 15 Transplant: Feb 5 🍅 Harvest: Apr 9 – Jun 18
Safe Start (90%) ✓ Fits season (161 days to spare)
Start indoors: Feb 10 Transplant: Mar 3 🍅 Harvest: May 5 – Jul 14

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 San Patricio County

How your county's soil matches Fennel (herb)'s growing requirements.

Soil pH

Your soil pH (6.8–7.2) overlaps with Fennel (herb)'s range (5.5–7.0), though not a perfect match.

Soil Texture

The loam soil in San Patricio County is excellent for Fennel (herb) — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is low (1.9%). Add 2-3 inches of compost before planting Fennel (herb).

How to Plant Fennel (herb)

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

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Fennel (herb)

6
successive plantings in your 300-day season

Sow every 6.9 weeks. Last sowing by Sep 10 to harvest before frost.

For a dedicated fall crop, sow by Oct 14.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 634 gal / 100 sq ft

Monthly Watering Guide for Fennel (herb)

Fennel (herb) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Fennel (herb) Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 4.3" 1.7" 2.6" 🚿 Regular watering
Mar 4.3" 3.8" 0.5" 💧 Light watering
Apr 4.3" 6.4" 0" ✅ Rainfall sufficient
May 4.3" 8.5" 0" ✅ Rainfall sufficient
Jun 4.3" 8.1" 0" ✅ Rainfall sufficient
Jul 4.3" 7.5" 0" ✅ Rainfall sufficient
Aug 4.3" 5.6" 0" ✅ Rainfall sufficient
Sep 4.3" 5" 0" ✅ Rainfall sufficient
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 4.3" 2" 2.3" 🚿 Regular watering
Dec 4.3" 1.4" 2.9" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in San Patricio County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Fennel (herb) 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 (herb) needs ~1,875 GDD — county provides 7,525 GDD Excellent fit

Fennel (herb) Planting Timeline — San Patricio County, TX

Fennel (herb) Planting Calendar

Activity When Date Range
Start Indoors January 15 Jan 15 – Jan 29
Transplant Outdoors February 5 Feb 5 – Feb 19
Direct Sow January 22 Jan 22 – Feb 12
Harvest April 9 Apr 9 – Jun 18
Fall Sowing October 14 Oct 14 – Oct 28

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

300 days in San Patricio County

Growing Tips for Fennel (herb) in San Patricio County

Direct sow Fennel (herb) outdoors after February 12 in San Patricio County when soil has warmed and frost danger has passed.

With summer highs reaching 100°F in San Patricio County, provide afternoon shade for Fennel (herb) and water deeply in the morning.

Common pests for Fennel (herb) 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 spring or fall. Unlike Florence fennel, herb fennel does not form a bulb. Harvest fronds as needed and seeds when they turn brown. Self-sows readily.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Peppers
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Fennel (herb) in San Patricio County, TX?

San Patricio County is in Zone 9b with an average last frost of February 12. Plan your Fennel (herb) planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Patricio County, TX?

San Patricio County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 12 and first fall frost is December 9.

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Your San Patricio County Garden Planner — Free

A 24-page printable planner built for San Patricio County (Zone 9b). 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 San Patricio 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.