When to plant onions in Louisiana
Louisiana’s average last spring frost is March 5, and the first fall frost typically arrives around November 15 — about 255 frost-free days (USDA zones 8a, 8b, 9a, 9b). Onion needs 90–120 days to mature, which fits comfortably within Louisiana's growing season.
When to plant onions in Louisiana: the short answer
For a spring planting, plant out Feb 5 – Feb 22, with seeds started indoors Dec 18 – Jan 1. Seeds germinate in soil from 40 to 90°F.
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow onions in Louisiana, step by step
- Start seeds indoors (Dec 18 – Jan 1). Sow seeds ½ inch deep in seed-starting mix under bright light. They take 7-14 days to sprout, fastest in soil around 70°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. They need at least six to eight hours of direct sun a day and loose soil at least 12 inches deep, with a pH between 6.0 and 7.0. Dig in compost before planting.
- Plant out (Feb 5 – Feb 22). Space plants about 4 inches apart in rows 12 inches apart. It handles frost well, so it can go out before the last frost date. As a cool-season crop it does best before summer heat arrives in Louisiana.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: onion maggot, onion thrips. Diseases and disorders: downy mildew, white rot, neck rot, purple blotch.
- Harvest (from about May 13 – Jun 12). Onion takes 90-120 days to reach harvest. Match the day-length type to your latitude: long-day onions for the north, short-day for the south, day-neutral anywhere. Bulbing is triggered by day length, not calendar date.
Figures come from our crop data; dates use Louisiana’s average frost dates. More in the full onion growing guide.
Onion planting dates by USDA zone in Louisiana
Louisiana spans USDA zones 8a, 8b, 9a, 9b. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average, so the onion dates shift with them.
When to plant onions in nearby states
| State | Last frost | Plant out |
|---|---|---|
| Louisiana (this page) | March 5 | Feb 5 – Feb 22 |
| Alabama | March 25 | Feb 25 – Mar 14 |
| Mississippi | March 20 | Feb 20 – Mar 9 |
| Florida | February 12 | Jan 15 – Feb 1 |
| Arkansas | April 3 | Mar 6 – Mar 23 |
Questions gardeners in Louisiana ask
When is the best time to plant onions in Louisiana?
Plant onion transplants outdoors in Louisiana between February 5 and February 22. That timing is set by Louisiana's average last spring frost of March 5.
When should I start onion seeds indoors in Louisiana?
Start seeds indoors between December 18 and January 1, about 10 weeks before the last frost, so the seedlings are ready to plant out from February 5.
When will onions planted in Louisiana be ready to harvest?
Planted on time, onions are usually ready from about May 13 to June 12, 90-120 days after transplanting.
When is the last frost in Louisiana?
On average around March 5, with the first fall frost around November 15 - about 255 frost-free days. Your town may differ by two weeks or more.