When to Plant Onions in Mississippi
Published: April 21, 2026
Mississippi gardeners in Zone 8a enjoy an extended 41-week growing season for onion. Cool-season crops like onion do best in fall, winter, and early spring in Mississippi — the hot summers bolt these plants before they can be harvested. This guide gives exact dates for Mississippi based on your local frost calendar.
Onion Planting Dates for Mississippi
| Start seeds indoors | December 7–14 |
| Last frost (average) | February 15 |
| Transplant outdoors | January 18–28 |
| Direct sow outdoors | January 18–28 |
| Expect first harvest | April 18 – May 18 |
| First fall frost (average) | December 1 |
Dates above assume Zone 8a, the most common zone in Mississippi. Gardeners in cooler Jackson (Zone 8a) plant 1–2 weeks later; warmer Gulfport (Zone 8b) 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 Mississippi's Climate
Mississippi's warm Zone 8a climate makes onion a fall, winter, and early spring crop rather than a summer one. The cool-season window runs roughly October through April in Mississippi — plant outside this window and the onion will bolt (send up a flower stalk and turn bitter) before it produces a harvestable crop.
Succession planting stretches the onion harvest window. Sow small amounts every two weeks from October through February — you will have staggered harvests rather than a single wave to process all at once. Bolt-resistant varieties extend the usable window an extra three to four weeks into warming weather.
Common onion pests to watch for in Mississippi 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 Mississippi
| Month | Task | Notes |
|---|---|---|
| January | Transplant outdoors | Soil temp must be 35°F+; nighttime lows above 50°F |
| February | Harden off seedlings | Set seedlings outdoors 1–2 hours daily, increasing gradually |
| March | — | Off-season |
| April | First harvest window opens | Onion begins producing 90–120 days after transplant |
| May ← | Watch for bolting | Harvest promptly; spring heat arrives quickly |
| June | — | Off-season |
| July | — | Off-season |
| August | — | Off-season |
| September | — | Off-season |
| October | — | Off-season |
| November | — | Off-season |
| December | Start seeds indoors | Use grow lights; warm soil to 70–75°F for best germination |
Onion Growing Tips for Mississippi 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.
- •Mississippi's cool-season onion plants best in October, November, and December for winter and early spring harvest. Spring plantings bolt before producing a harvestable crop.
- •Reduce watering as tops begin to fall over — dry conditions encourage tight, firm bulbs that store longer.
Companion Planting for Onions in Mississippi
In Mississippi's warm 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 Mississippi
Top cities in Mississippi — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant onion in Mississippi?
In Mississippi (Zone 8a), start onion seeds indoors around December 7–14 and transplant outdoors around January 18–28 — 4 weeks before the state's average last frost of February 15.
What is the last frost date in Mississippi?
Mississippi's average last frost date is February 15 in the state's most common Zone 8a. 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 Mississippi?
onion is a cool-season crop in Mississippi, 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 Mississippi?
For Mississippi's Zone 8a, Short-day varieties like Texas 1015, Granex, and Yellow Bermuda bulb under the 10–12 hour days south of 35°N.
When do I start onion seeds indoors in Mississippi?
Start onion seeds indoors in Mississippi around December 7–14, which is 10 weeks before the state's average last frost of February 15. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.