When to Plant Onions in Alabama
Published: April 21, 2026
Alabama gardeners in Zone 7b have a 38-week growing season for onion (March 1 to November 22). Alabama's spring and fall windows both work well for onion — some gardeners plant both successions for a long harvest. This guide gives exact dates for Alabama based on your local frost calendar.
Onion Planting Dates for Alabama
| Start seeds indoors | December 21–28 |
| Last frost (average) | March 1 |
| Transplant outdoors | February 1–11 |
| Direct sow outdoors | February 1–11 |
| Expect first harvest | May 2 – June 1 |
| First fall frost (average) | November 22 |
Dates above assume Zone 7b, the most common zone in Alabama. Gardeners in cooler Birmingham (Zone 7b) plant 1–2 weeks later; warmer Montgomery (Zone 8a) can plant 1–2 weeks earlier.
⚠ CRITICAL: Choose variety based on your latitude. Short-day varieties for south of 35°N (Texas, Florida, California). Long-day varieties for north of 35°N (Ohio, Minnesota, New York). Intermediate varieties work in the middle band.
Growing Onions in Alabama's Climate
Alabama's moderate Zone 7b climate is well-suited to onion with minimal special accommodation. The standard transplant calendar works as written, and harvest windows line up with what seed packets recommend without adjustment.
Succession planting extends your onion harvest significantly in Alabama. A second planting 3 to 4 weeks after the first gives you a backup in case of pest pressure and extends the total harvest window into early fall.
Common onion pests to watch for in Alabama include Onion Thrips and Onion Maggot. The first line of defense is companion planting: Carrot and Tomato planted nearby discourage several of these pests by confusing host-plant identification or repelling adults before they can lay eggs. Weekly garden walks in the early morning catch problems when they're still manageable.
Onion Garden Calendar for Alabama
| Month | Task | Notes |
|---|---|---|
| January | — | Dormant season |
| February | Transplant outdoors | Soil temp must be 35°F+; nighttime lows above 50°F |
| March | Harden off seedlings | Set seedlings outdoors 1–2 hours daily, increasing gradually |
| April | — | Dormant season |
| May ← | Watch for bolting | Harvest promptly; spring heat arrives quickly |
| June | — | Dormant season |
| July | — | Dormant season |
| August | — | Dormant season |
| September | — | Dormant season |
| October | — | Dormant season |
| November | First frost approaches | Harvest remaining onion; cover plants on frost nights |
| December | Start seeds indoors | Use grow lights; warm soil to 70–75°F for best germination |
Onion Growing Tips for Alabama Gardeners
- •Match variety to latitude: short-day south of 35°N, long-day north of 35°N, intermediate in between.
- •Growing from sets (small bulbs) is fastest; growing from transplants gives the most variety options.
- •Alabama's moderate climate supports succession planting — sow new transplants or seeds every 3 weeks during spring to extend the harvest window into fall.
- •Reduce watering as tops begin to fall over — dry conditions encourage tight, firm bulbs that store longer.
Companion Planting for Onions in Alabama
In Alabama's moderate climate, planting onion with Carrot and Tomato helps deter pests and improve soil. Avoid planting near Bean and Pea, which inhibit onion growth through root chemistry or shared pest pressure. See the full onion companion planting guide for the complete list.
Onions Planting Dates by City in Alabama
Top cities in Alabama — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant onion in Alabama?
In Alabama (Zone 7b), start onion seeds indoors around December 21–28 and transplant outdoors around February 1–11 — 4 weeks before the state's average last frost of March 1.
What is the last frost date in Alabama?
Alabama's average last frost date is March 1 in the state's most common Zone 7b. Frost dates vary by city — higher elevations and northern counties run 1 to 3 weeks later than the state average. See the city list below for city-level frost dates.
Can I grow onion year-round in Alabama?
onion is a cool-season crop in Alabama, with spring and fall windows. Summer heat bolts the plants before they can produce a harvestable crop. Succession planting every 2–3 weeks stretches the harvest window.
What onion varieties grow best in Alabama?
For Alabama's Zone 7b, Intermediate-day varieties (Candy, Super Star) work best in the 35–38°N band.
When do I start onion seeds indoors in Alabama?
Start onion seeds indoors in Alabama around December 21–28, which is 10 weeks before the state's average last frost of March 1. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.