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When to Plant Onion in Ouachita Parish, LA

Ouachita Parish, Louisiana Zone 8b May

May in the garden — Ouachita Parish, Louisiana

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Ouachita Parish, Louisiana.

Avg. last frost March 10
Avg. first frost November 12
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 13.7 hrs
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.

Ouachita Parish, Louisiana is in USDA Zone 8b. The average last spring frost is March 10 and the first fall frost is November 12, giving you a growing season of approximately 247 days.

At an elevation of 340 feet, Ouachita Parish receives approximately 53.7 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.

Ouachita Parish, LA (Zone 8b) Long season
247 days
Last Spring Frost March 10
247 growing days
First Fall Frost November 12

Ouachita Parish Soil Profile

Soil Type

Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (104 days to spare)
Start indoors: Jan 28 Transplant: Mar 4 🍅 Harvest: Jun 3 – Jul 22
Recommended (50%) ✓ Fits season (107 days to spare)
Start indoors: Feb 3 Transplant: Mar 10 🍅 Harvest: Jun 9 – Jul 28
Safe Start (90%) ✓ Fits season (97 days to spare)
Start indoors: Mar 3 Transplant: Apr 7 🍅 Harvest: Jul 7 – 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 Ouachita Parish

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

Soil pH

Your soil pH (6.3–6.8) is within Onion's preferred range (6.0–7.0).

Soil Texture

The loam soil in Ouachita Parish is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help 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
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 191 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 5.1" 0" ❄️ Dormant
Feb 4.9" 0" ❄️ Dormant
Mar 4.3" 4.4" 0" ✅ Rainfall sufficient
Apr 4.3" 4" 0.3" 💧 Light watering
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 5" 0" ✅ Rainfall sufficient
Jul 4.3" 5" 0" ✅ Rainfall sufficient
Aug 4.3" 4.9" 0" ✅ Rainfall sufficient
Sep 4.3" 3.6" 0.7" 💧 Light watering
Oct 4.3" 3.6" 0.7" 💧 Light watering
Nov 4.3" 4.2" 0.1" 💧 Light watering
Dec 4.4" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Ouachita Parish). 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 4,693 GDD Excellent fit

Onion Planting Timeline — Ouachita Parish, LA

Onion Planting Calendar

Activity When Date Range
Start Indoors February 3 Feb 3 – Feb 17
Transplant Outdoors March 10 Mar 10 – Mar 24
Direct Sow February 24 Feb 24 – Mar 17
Harvest June 9 Jun 9 – Jul 28
Fall Sowing September 3 Sep 3 – Sep 17

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 8b

📆 Growing Season

247 days in Ouachita Parish

Growing Tips for Onion in Ouachita Parish

Direct sow Onion outdoors after March 10 in Ouachita Parish 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 Ouachita Parish, LA?

Ouachita Parish is in Zone 8b with an average last frost of March 10. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ouachita Parish, LA?

Ouachita Parish, Louisiana is in USDA Hardiness Zone 8b. The average last spring frost is March 10 and first fall frost is November 12.

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Your Ouachita Parish Garden Planner — Free

A 24-page printable planner built for Ouachita Parish (Zone 8b). 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 Ouachita Parish, LA. 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.