When to Plant Tomatoes in Arizona
Published: April 21, 2026
Arizona gardeners in Zone 9b enjoy an extended 50-week growing season for tomato. Warm-climate gardeners can grow two tomato crops — a spring planting and a fall planting — with summer heat as the main challenge to work around. This guide gives exact dates for Arizona based on your local frost calendar.
Tomato Planting Dates for Arizona
| Start seeds indoors | December 4–11 |
| Last frost (average) | January 15 |
| Transplant outdoors | January 29–February 8 |
| Expect first harvest | March 30 – April 24 |
| Fall crop start | October 8–18 |
| Fall harvest | December 7 |
| 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.
⚠ Warm-climate gardeners (TX, FL, AZ) can grow TWO crops: spring (Feb–March transplant) and fall (July transplant for October harvest).
Growing Tomatoes in Arizona's Climate
Arizona's warm Zone 9b climate gives tomato more than enough heat — in fact, peak summer heat (95°F+) can shut down fruit set entirely. The solution most Arizona gardeners use is a two-season approach: a spring crop planted early, a harvest break during peak summer, and a fall crop planted July through August for October and November harvest.
Variety selection matters more in warm climates than most gardeners realize. Choose heat-tolerant varieties bred for Arizona-like conditions — local extension offices and nurseries stock these specifically. Afternoon shade cloth during July and August can be the difference between a working fall crop and total flower drop.
Common tomato pests to watch for in Arizona include Tomato Hornworm and Aphids. The first line of defense is companion planting: Basil and Marigold 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.
Tomato Garden Calendar for Arizona
| Month | Task | Notes |
|---|---|---|
| January | Transplant outdoors | Soil temp must be 60°F+; nighttime lows above 50°F |
| February | — | Off-season |
| March | First harvest window opens | Tomato begins producing 60–85 days after transplant |
| April | — | Off-season |
| May ← | — | Off-season |
| June | Peak growth; water 1 inch/week | Monitor for pests daily; stake or support as needed |
| July | Start fall crop seeds | Fall transplants go in 12 weeks before first frost |
| August | — | Off-season |
| September | — | Off-season |
| October | Fall crop planting | Transplant or direct sow for fall harvest before frost |
| November | — | Off-season |
| December | Start seeds indoors | Use grow lights; warm soil to 70–75°F for best germination |
Tomato Growing Tips for Arizona Gardeners
- •Bury the stem 2/3 deep when transplanting — roots grow from the buried stem for a stronger plant.
- •Consistent watering prevents blossom end rot and fruit cracking; uneven moisture causes both.
- •Arizona's summer heat shuts down tomato flowering at 95°F+. Choose heat-tolerant varieties and use shade cloth from mid-June through August to preserve fruit set.
- •Arizona's fall crop is often more productive than spring — plant transplants in July after the worst heat, for October and November harvest as temperatures cool.
- •Stop heavy nitrogen once flowers appear — it causes leafy plants with few tomatoes.
Companion Planting for Tomatoes in Arizona
In Arizona's warm climate, planting tomato with Basil and Marigold helps deter pests and improve soil. Avoid planting near Potato and Fennel, which inhibit tomato growth through root chemistry or shared pest pressure. See the full tomato companion planting guide for the complete list.
Tomatoes 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 tomato in Arizona?
In Arizona (Zone 9b), start tomato seeds indoors around December 4–11 and transplant outdoors around January 29–February 8 — 2 weeks after 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 tomato year-round in Arizona?
Not year-round — Arizona's cold season stops tomato production. The tomato season runs January 15 to December 31, roughly 50 weeks. A fall crop extends harvest into late autumn.
What tomato varieties grow best in Arizona?
For Arizona's Zone 9b, Heat-tolerant varieties like Heatmaster, Sun Gold, Celebrity, and Sweet 100 set fruit in high temperatures that stop other varieties.
When do I start tomato seeds indoors in Arizona?
Start tomato seeds indoors in Arizona around December 4–11, which is 6 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.