When to Plant Onions in Nevada
Published: April 21, 2026
Nevada gardeners in Zone 9a enjoy an extended 46-week growing season for onion. Cool-season crops like onion do best in fall, winter, and early spring in Nevada — the hot summers bolt these plants before they can be harvested. This guide gives exact dates for Nevada based on your local frost calendar.
Onion Planting Dates for Nevada
| Start seeds indoors | November 21–28 |
| Last frost (average) | January 30 |
| Transplant outdoors | January 2–12 |
| Direct sow outdoors | January 2–12 |
| Expect first harvest | April 2 – May 2 |
| First fall frost (average) | December 15 |
Dates above assume Zone 9a, the most common zone in Nevada. Gardeners in cooler Reno (Zone 6a) plant 1–2 weeks later; warmer Las Vegas (Zone 9a) 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 Nevada's Climate
Nevada's warm Zone 9a 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 Nevada — 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 Nevada 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 Nevada
| Month | Task | Notes |
|---|---|---|
| January | Transplant outdoors | Soil temp must be 35°F+; nighttime lows above 50°F |
| February | — | Off-season |
| 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 | Start seeds indoors | Use grow lights; warm soil to 70–75°F for best germination |
| December | First frost approaches | Harvest remaining onion; cover plants on frost nights |
Onion Growing Tips for Nevada 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.
- •Nevada'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 Nevada
In Nevada'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 Nevada
Top cities in Nevada — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant onion in Nevada?
In Nevada (Zone 9a), start onion seeds indoors around November 21–28 and transplant outdoors around January 2–12 — 4 weeks before the state's average last frost of January 30.
What is the last frost date in Nevada?
Nevada's average last frost date is January 30 in the state's most common Zone 9a. 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 Nevada?
onion is a cool-season crop in Nevada, 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 Nevada?
For Nevada's Zone 9a, 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 Nevada?
Start onion seeds indoors in Nevada around November 21–28, which is 10 weeks before the state's average last frost of January 30. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.