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When to Plant Fennel in Sterling County, TX

Sterling County, Texas Zone 8a May

This month in Sterling County, Texas

Your Sterling County, Texas garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost March 24
Avg. first frost November 12
Soil temp (4") 63°F
Watering High
Pest pressure Moderate
Daylight 13.6 hrs
  1. Get fennel seeds going inside

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

Coming up in June — start thinking about
  • 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.

Sterling County, Texas is in USDA Zone 8a. The average last spring frost is March 24 and the first fall frost is November 12, giving you a growing season of approximately 233 days.

At an elevation of 2,929 feet, Sterling County receives approximately 50.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 99°F, so Fennel may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Fennel will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Fennel root diseases.

Sterling County, TX (Zone 8a) Long season
233 days
Last Spring Frost March 24
233 growing days
First Fall Frost November 12

Sterling County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.4-8.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (122 days to spare)
Start indoors: Jan 19 Transplant: Mar 23 🍅 Harvest: May 25 – Jul 6
Recommended (50%) ✓ Fits season (114 days to spare)
Start indoors: Feb 3 Transplant: Apr 7 🍅 Harvest: Jun 9 – Jul 21
Safe Start (90%) ✓ Fits season (109 days to spare)
Start indoors: Feb 24 Transplant: Apr 28 🍅 Harvest: Jun 30 – Aug 11

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 Sterling County

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

Soil pH

Your soil pH (7.4–8.6) is more alkaline than Fennel prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Sterling County warms quickly in spring but drains fast. Fennel will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is low (0.9%). Add 2-3 inches of compost before planting Fennel.

How to Plant Fennel

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

Succession Planting Fennel

4
successive plantings in your 233-day season

Sow every 6.9 weeks. Last sowing by Aug 14 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 8/10 — 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 3.5" 0" ❄️ Dormant
Feb 2.7" 0" ❄️ Dormant
Mar 2.6" 2.8" 0" ✅ Rainfall sufficient
Apr 2.6" 1.9" 0.7" 💧 Light watering
May 2.6" 1.3" 1.3" 🚿 Regular watering
Jun 2.6" 1.9" 0.7" 💧 Light watering
Jul 2.6" 8.9" 0" ✅ Rainfall sufficient
Aug 2.6" 9.4" 0" ✅ Rainfall sufficient
Sep 2.6" 7.9" 0" ✅ Rainfall sufficient
Oct 2.6" 4.2" 0" ✅ Rainfall sufficient
Nov 2.6" 3" 0" ✅ Rainfall sufficient
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Sterling 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 ~1,819 GDD — county provides 5,650 GDD Excellent fit

Fennel Planting Timeline — Sterling County, TX

Fennel Planting Calendar

Activity When Date Range
Start Indoors February 3 Feb 3 – Feb 17
Transplant Outdoors April 7 Apr 7 – Apr 21
Direct Sow March 31 Mar 31 – Apr 21
Harvest June 9 Jun 9 – Jul 21

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 8a

📆 Growing Season

233 days in Sterling County

Growing Tips for Fennel in Sterling County

Direct sow Fennel outdoors after March 24 in Sterling County when soil has warmed and frost danger has passed.

Sandy soil in Sterling County dries quickly — mulch Fennel with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 99°F in Sterling County, provide afternoon shade for Fennel and water deeply in the morning.

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 Sterling County, TX?

Sterling County is in Zone 8a with an average last frost of March 24. Plan your Fennel planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sterling County, TX?

Sterling County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 24 and first fall frost is November 12.

🌱

Your Sterling County Garden Planner — Free

A 24-page printable planner built for Sterling County (Zone 8a). 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 Sterling 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.