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When to Plant Onion in Lamb County, TX

Lamb County, Texas Zone 7a May

May to-do list for Lamb County, Texas

Your Lamb 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 April 8
Avg. first frost October 27
Soil temp (4") 66°F
Watering Critical
Pest pressure Moderate
Daylight 13.8 hrs
  1. Indoor seed-starting week for onion

    Label every cell. You will absolutely forget which is which otherwise.

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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.

Lamb County, Texas is in USDA Zone 7a. The average last spring frost is April 8 and the first fall frost is October 27, giving you a growing season of approximately 202 days.

At an elevation of 1,440 feet, Lamb County receives approximately 56.5 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°F, so Onion may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Onion will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Onion root diseases.

Lamb County, TX (Zone 7a) Long season
202 days
Last Spring Frost April 8
202 growing days
First Fall Frost October 27

Lamb County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.5-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (58 days to spare)
Start indoors: Feb 27 Transplant: Apr 3 🍅 Harvest: Jul 3 – Aug 21
Recommended (50%) ✓ Fits season (62 days to spare)
Start indoors: Mar 4 Transplant: Apr 8 🍅 Harvest: Jul 8 – Aug 26
Safe Start (90%) ✓ Fits season (62 days to spare)
Start indoors: Mar 23 Transplant: Apr 27 🍅 Harvest: Jul 27 – Sep 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 Lamb County

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

Soil pH

Your soil pH (7.5–8.4) is more alkaline than Onion prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Lamb County warms quickly in spring but drains fast. Onion 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 Onion.

How to Plant Onion

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/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 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 3.9" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 3.5" 0" ❄️ Dormant
Apr 4.3" 2" 2.3" 🚿 Regular watering
May 4.3" 1.2" 3.1" 🚿 Regular watering
Jun 4.3" 2" 2.3" 🚿 Regular watering
Jul 4.3" 8.9" 0" ✅ Rainfall sufficient
Aug 4.3" 11.2" 0" ✅ Rainfall sufficient
Sep 4.3" 8.8" 0" ✅ Rainfall sufficient
Oct 4.3" 5.2" 0" ✅ Rainfall sufficient
Nov 3.4" 0" ❄️ Dormant
Dec 3.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Lamb 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 ~2,310 GDD — county provides 4,444 GDD Excellent fit

Onion Planting Timeline — Lamb County, TX

Onion Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 – Mar 18
Transplant Outdoors April 8 Apr 8 – Apr 22
Direct Sow March 25 Mar 25 – Apr 15
Harvest July 8 Jul 8 – Aug 26
Fall Sowing August 18 Aug 18 – Sep 1

Plant 1" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7a

📆 Growing Season

202 days in Lamb County

Growing Tips for Onion in Lamb County

Direct sow Onion outdoors after April 08 in Lamb County when soil has warmed and frost danger has passed.

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

With summer highs reaching 96°F in Lamb County, provide afternoon shade for Onion and water deeply in the morning.

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 Lamb County, TX?

Lamb County is in Zone 7a with an average last frost of April 8. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lamb County, TX?

Lamb County, Texas is in USDA Hardiness Zone 7a. The average last spring frost is April 8 and first fall frost is October 27.

🌱

Your Lamb County Garden Planner — Free

A 24-page printable planner built for Lamb County (Zone 7a). 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 Lamb 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.