When To Plant Onions In Louisiana

Getting your onion planting timing right is the single biggest factor for a succesful harvest here. If you’re wondering when to plant onions in Louisiana, you’re already on the right track. Our unique climate, split between north and south regions, means we have two distinct planting windows. Planting at the correct time ensures your bulbs have enough cool weather to grow large before the heat triggers them to start bulbing.

Louisiana’s ideal planting schedule depends heavily on whether you live in north or south Louisiana. Onions are a cool-season crop, and our goal is to get them established and growing during the cooler months. This gives them a strong foundation before the long, warm days of late spring tell them it’s time to form bulbs.

North Louisiana Planting Dates

For gardeners in the northern part of the state, the primary planting period is in the fall. You’ll want to get your onions in the ground between October 15th and November 15th. Fall planting allows the onion plants to develop a robust root system and some top growth before winter dormancy. They’ll then resume vigorous growth very early in the spring, giving them a long head start.

Optimal Window: October 15 – November 15
Method: Primarily from transplants (sets or seedlings).
Goal: Establish roots before winter for early spring growth.

South Louisiana Planting Dates

In the warmer southern parishes, the main planting time is in late winter. Aim to plant between January 15th and February 15th. The soil is cool but workable, and the plants will have several months of ideal growing conditions before the intense summer heat arrives. This schedule is perfect for growing large, sweet onions.

Optimal Window: January 15 – February 15
Method: Transplants are best; seeds can be started earlier indoors.
Goal: Utilize the extended cool spring period for bulb development.

Understanding Onion Types: Short-Day vs. Long-Day

Choosing the right type of onion is just as crucial as the planting date. Onions are categorized by how much daylight they need to form a bulb, known as “photoperiod.”

Short-Day Onions: These are the champions for Louisiana. They begin forming bulbs when daylight lasts 10-12 hours. Our spring days are perfect for them. Popular varieties include Texas Legend, Texas Supersweet, Red Creole, and the famous Vidalia-type onions like Granex.
Intermediate-Day Onions: These need 12-14 hours of daylight and can also perform well, especially in north Louisiana. Varieties like Candy and Super Star are reliable choices.
Long-Day Onions: Avoid these for Louisiana gardens. They need 14-16 hours of daylight to bulb, which our southern latitude doesn’t provide. They will only produce greens, not bulbs.

Step-by-Step Planting Guide

Once you have your timing and variety sorted, follow these steps for a great start.

1. Preparing Your Soil

Onions need loose, well-draining soil rich in organic matter. They are heavy feeders, so proper bed preparation is key.

Choose a site with full sun—at least 6-8 hours of direct light.
Work the soil to a depth of 8-10 inches, breaking up any clods.
Mix in 2-3 inches of compost or well-rotted manure. Add a balanced fertilizer (like 10-10-10) according to package directions.
Raised beds are an excellent option in Louisiana to improve drainage, especially during our wet winters and springs.

2. Choosing Your Planting Material

You can plant onions from seeds, sets (small bulbs), or transplants (seedlings). For most Louisiana gardeners, transplants are the most reliable and easiest method for the main planting seasons. Sets are also easy but can be more prone to bolting (flowering prematurely). Starting from seed gives the most variety but requires more time and care.

3. The Planting Process

Create rows spaced about 12-18 inches apart.
For transplants and sets, plant them about 1 inch deep. If the transplant has long greens, you can trim them back to about 4 inches to reduce transplant shock and prevent wind damage.
Space plants 4-6 inches apart within the row. Wider spacing allows for larger bulbs.
Firm the soil gently around each plant and water them in thoroughly.

Essential Care Through the Season

Watering and Mulching

Consistent moisture is vital for good bulb development. Onions have shallow roots, so they dry out quickly. Water deeply when the top inch of soil feels dry, providing about 1 inch of water per week. A layer of straw or pine straw mulch helps retain soil moisture, suppress weeds, and keep the soil temperature even. Mulch is especially helpful for fall-planted onions to protect them from freeze-thaw cycles.

Fertilizing for Success

Feed your onions regularly to support their rapid growth. Apply a nitrogen-rich fertilizer (like ammonium sulfate or a balanced fertilizer) every 2-3 weeks until the bulbs begin to form. Once you see the soil start to crack and push away as the bulb expands, stop fertilizing. This allows the bulb to mature properly and develop good storage qualities.

Weed Control

Onions hate competition. Weeds will rob them of nutrients and water. Hand-pull weeds carefully to avoid disturbing the onion’s shallow roots. Mulching heavily is the best defense against weeds.

Common Problems and Solutions

Louisiana’s humidity can create some challenges. Here’s what to watch for:

Bolting: This is when an onion sends up a flower stalk. It’s often caused by temperature fluctuations or planting the wrong type. Once an onion bolts, the bulb stops growing and won’t store well. You can still use it, but harvest it soon. Choose bolt-resistant varieties and plant at the correct time to minimize risk.
Pests: Thrips are tiny insects that can cause silvery streaks on leaves. Control them with a strong spray of water or insecticidal soap. Onion maggots are less common but can damage bulbs; crop rotation helps prevent them.
Diseases: Fungal diseases like downy mildew or purple blotch can occur in wet weather. Ensure good air circulation by proper spacing, water at the base of plants (not overhead), and remove any infected plants promptly.

Harvesting and Curing Your Onions

Knowing when to harvest is simple. In late spring or early summer, you’ll notice the tops of the onions start to turn yellow and fall over. This is the plant’s natural sign that it’s finished growing.

Once about half the tops have fallen, gently push over the remaining tops to signal the plant to stop growing.
Wait for a dry, sunny spell to harvest. Carefully lift the bulbs from the soil with a garden fork.
Curing is non-negotiable for storage. Lay the bulbs in a single layer in a warm, dry, well-ventilated place out of direct sun—like a covered porch or garage. Let them cure for 2-3 weeks until the necks are tight and dry and the outer skins are papery.
After curing, trim the roots and cut the tops back to about 1 inch. Store in a cool, dry, dark place in mesh bags or a single layer.

Louisiana Onion Planting FAQ

Can I plant onions in the spring in North Louisiana?

Yes, but it’s a secondary, shorter-season crop. Plant as early as the soil can be worked in February. Use short-day varieties and expect smaller bulbs, perfect for fresh eating.

What are the best onion varieties for Louisiana?

Stick with proven short-day varieties: Texas Legend (yellow, great storage), Red Creole (red, good storage), Granex 33 (white, sweet, Vidalia-type), and Southern Belle Red (a reliable red).

How deep should I plant onion sets?

Plant sets just deep enough so the tip is level with the soil surface, about 1 inch deep. Planting them to deep can restrict bulb formation.

Why are my onions so small?

Small bulbs are usually caused by late planting, overcrowding, insufficient fertilizer (especially nitrogen), or inconsistent watering. Getting them in the ground on time is the most common fix.

Can I grow onions in containers?

Absolutely. Choose a container at least 10 inches deep and wide. Use a quality potting mix, ensure excellent drainage, and water frequently as pots dry out fast. Plant at the same spacing you would in a garden bed.

Following Louisiana’s ideal planting schedule for onions sets you up for a bountiful harvest. By matching the right short-day variety with the correct fall or winter planting window for your region, you give your onions the best possible start. With consistent care through the season and proper curing at harvest, you’ll be enjoying homegrown onions from your pantry long after the garden is done. There’s nothing quite like the flavor of an onion you grew yourself.