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When to Plant Leeks in San Patricio County, TX

San Patricio County, Texas Zone 9b May

What to do in May

We've pulled the most time-sensitive tasks for San Patricio County, Texas this May and put them front and centre. Tackle them in order.

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 leeks

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

A few tasks this May that'll pay off in June
  • First harvests: leeks

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Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.

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 Leeks may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Leeks 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
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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 (147 days to spare)
Start indoors: Dec 23 Transplant: Jan 20 🍅 Harvest: Apr 21 – Jul 7
Recommended (50%) ✓ Fits season (132 days to spare)
Start indoors: Jan 15 Transplant: Feb 12 🍅 Harvest: May 14 – Jul 30
Safe Start (90%) ✓ Fits season (119 days to spare)
Start indoors: Feb 10 Transplant: Mar 10 🍅 Harvest: Jun 9 – Aug 25

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 Leeks's growing requirements.

Soil pH

Your soil pH (6.8–7.2) overlaps with Leeks's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Leeks

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

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

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.8″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 98 gal / 100 sq ft

Monthly Watering Guide for Leeks

Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Leeks Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 3.5" 1.7" 1.8" 🚿 Regular watering
Mar 3.5" 3.8" 0" ✅ Rainfall sufficient
Apr 3.5" 6.4" 0" ✅ Rainfall sufficient
May 3.5" 8.5" 0" ✅ Rainfall sufficient
Jun 3.5" 8.1" 0" ✅ Rainfall sufficient
Jul 3.5" 7.5" 0" ✅ Rainfall sufficient
Aug 3.5" 5.6" 0" ✅ Rainfall sufficient
Sep 3.5" 5" 0" ✅ Rainfall sufficient
Oct 3.5" 3.1" 0.4" 💧 Light watering
Nov 3.5" 2" 1.5" 💧 Light watering
Dec 3.5" 1.4" 2.1" 🚿 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.

Leeks 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.

Leeks needs ~3,000 GDD — county provides 7,525 GDD Excellent fit

Leeks Planting Timeline — San Patricio County, TX

Leeks Planting Calendar

Activity When Date Range
Start Indoors January 15 Jan 15 – Jan 29
Transplant Outdoors February 12 Feb 12 – Feb 26
Direct Sow January 22 Jan 22 – Feb 12
Harvest May 14 May 14 – Jul 30
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
May Harvest
June Harvest
July Harvest
August
September
October Fall Sowing
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Only during dry spells

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

300 days in San Patricio County

Growing Tips for Leeks in San Patricio County

Direct sow Leeks 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 Leeks and water deeply in the morning.

Common pests for Leeks in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Leeks in San Patricio County, TX?

San Patricio County is in Zone 9b with an average last frost of February 12. Plan your Leeks 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.

🌱

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.