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When to Plant Onion in La Salle County, TX

La Salle County, Texas Zone 9a May

Your May planting checklist for La Salle County, Texas

Each item below is timed to La Salle County, Texas's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost February 14
Avg. first frost December 3
Soil temp (4") 67°F
Watering Low
Pest pressure High
Daylight 13.4 hrs
  1. Pick onion

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

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

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Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.

La Salle County, Texas is in USDA Zone 9a. The average last spring frost is February 14 and the first fall frost is December 3, giving you a growing season of approximately 292 days.

At an elevation of 2,270 feet, La Salle County receives approximately 57.2 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Onion during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Onion root diseases.

La Salle County, TX (Zone 9a) Year-round
292 days
Last Spring Frost February 14
292 growing days
First Fall Frost December 3

La Salle County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (160 days to spare)
Start indoors: Jan 2 Transplant: Jan 30 🍅 Harvest: May 1 – Jun 19
Recommended (50%) ✓ Fits season (152 days to spare)
Start indoors: Jan 17 Transplant: Feb 14 🍅 Harvest: May 16 – Jul 4
Safe Start (90%) ✓ Fits season (141 days to spare)
Start indoors: Feb 14 Transplant: Mar 14 🍅 Harvest: Jun 13 – Aug 1

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 La Salle County

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

Soil pH

Your soil pH (6.5–7.6) is more alkaline than Onion prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in La Salle County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Onion.

Organic Matter

Organic matter is moderate (2.0%). Annual compost additions will help Onion.

How to Plant Onion

1"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 1,252 gal / 100 sq ft

Monthly Watering Guide for Onion

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

Month Onion Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 4.3" 2" 2.3" 🚿 Regular watering
Mar 4.3" 3.4" 0.9" 💧 Light watering
Apr 4.3" 5.5" 0" ✅ Rainfall sufficient
May 4.3" 7.4" 0" ✅ Rainfall sufficient
Jun 4.3" 10.2" 0" ✅ Rainfall sufficient
Jul 4.3" 7.3" 0" ✅ Rainfall sufficient
Aug 4.3" 7" 0" ✅ Rainfall sufficient
Sep 4.3" 5.8" 0" ✅ Rainfall sufficient
Oct 4.3" 3.6" 0.7" 💧 Light watering
Nov 4.3" 2" 2.3" 🚿 Regular watering
Dec 4.3" 1.6" 2.7" 🚿 Regular watering

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

Onion 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.

Onion needs ~1,995 GDD — county provides 5,567 GDD Excellent fit

Onion Planting Timeline — La Salle County, TX

Onion Planting Calendar

Activity When Date Range
Start Indoors January 17 Jan 17 – Jan 31
Transplant Outdoors February 14 Feb 14 – Feb 28
Direct Sow January 24 Jan 24 – Feb 14
Harvest May 16 May 16 – Jul 4
Fall Sowing October 8 Oct 8 – Oct 22

Plant 1" deep · 6" apart · Rows 12" 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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9a

📆 Growing Season

292 days in La Salle County

Growing Tips for Onion in La Salle County

Direct sow Onion outdoors after February 14 in La Salle County when soil has warmed and frost danger has passed.

Common pests for Onion 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 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Onion in La Salle County, TX?

La Salle County is in Zone 9a with an average last frost of February 14. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is La Salle County, TX?

La Salle County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 14 and first fall frost is December 3.

🌱

Your La Salle County Garden Planner — Free

A 24-page printable planner built for La Salle 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 La Salle 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.