When to Plant Lettuce in Arizona
Published: April 21, 2026
Arizona gardeners in Zone 9b enjoy an extended 50-week growing season for lettuce. Cool-season crops like lettuce do best in fall, winter, and early spring in Arizona — the hot summers bolt these plants before they can be harvested. This guide gives exact dates for Arizona based on your local frost calendar.
Lettuce Planting Dates for Arizona
| Start seeds indoors | December 18–25 |
| Last frost (average) | January 15 |
| Transplant outdoors | December 18–28 |
| Direct sow outdoors | December 4–14 |
| Expect first harvest | January 17 – February 16 |
| Fall crop start | November 19–29 |
| Fall harvest | December 19 |
| First fall frost (average) | December 31 |
Dates above assume Zone 9b, the most common zone in Arizona. Gardeners in cooler San Tan Valley (Zone 7b) plant 1–2 weeks later; warmer Tucson (Zone 9a) can plant 1–2 weeks earlier.
Growing Lettuce in Arizona's Climate
Arizona's warm Zone 9b climate makes lettuce a fall, winter, and early spring crop rather than a summer one. The cool-season window runs roughly October through April in Arizona — plant outside this window and the lettuce will bolt (send up a flower stalk and turn bitter) before it produces a harvestable crop.
Succession planting stretches the lettuce 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 lettuce pests to watch for in Arizona include Aphids and Slugs. The first line of defense is companion planting: Carrot and Radish 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.
Lettuce Garden Calendar for Arizona
| Month | Task | Notes |
|---|---|---|
| January | Harden off seedlings | Set seedlings outdoors 1–2 hours daily, increasing gradually |
| February | — | Off-season |
| March | — | Off-season |
| April | — | Off-season |
| 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 | Fall crop planting | Transplant or direct sow for fall harvest before frost |
| December | Transplant outdoors | Soil temp must be 40°F+; nighttime lows above 50°F |
Lettuce Growing Tips for Arizona Gardeners
- •Direct sow very shallowly — lettuce seeds need light to germinate; cover with just 1/8 inch of soil.
- •Cut outer leaves 1 inch above the crown for "cut-and-come-again" harvests lasting weeks.
- •Arizona's cool-season lettuce plants best in October, November, and December for winter and early spring harvest. Spring plantings bolt before producing a harvestable crop.
- •Provide afternoon shade in warmer climates (Zones 7+) to extend the spring window before heat bolts plants.
Companion Planting for Lettuce in Arizona
In Arizona's warm climate, planting lettuce with Carrot and Radish helps deter pests and improve soil. Avoid planting near Fennel and Celery, which inhibit lettuce growth through root chemistry or shared pest pressure. See the full lettuce companion planting guide for the complete list.
Lettuce Planting Dates by City in Arizona
Top cities in Arizona — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant lettuce in Arizona?
In Arizona (Zone 9b), start lettuce seeds indoors around December 18–25 and transplant outdoors around December 18–28 — 4 weeks before the state's average last frost of January 15.
What is the last frost date in Arizona?
Arizona's average last frost date is January 15 in the state's most common Zone 9b. 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 lettuce year-round in Arizona?
lettuce is a cool-season crop in Arizona, 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 lettuce varieties grow best in Arizona?
For Arizona's Zone 9b, Bolt-resistant Jericho, Slobolt, and Summer Bibb extend the usable spring window.
When do I start lettuce seeds indoors in Arizona?
Start lettuce seeds indoors in Arizona around December 18–25, which is 4 weeks before the state's average last frost of January 15. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.