Planting Guides
When to Plant Tomatoes in Phoenix: Complete Guide + Best Varieties for Zone 9b
Phoenix, Arizona
USDA Zone 9b
Last Frost: Feb 15
Last updated: October 30, 2025
Plant tomatoes in Phoenix from mid-February through March for spring harvest, then again in August for fall production in Zone 9b's unique desert climate.
— Image © PlantReference.org 2026
Quick Answer
Plant tomatoes in Phoenix from February 15-March 15 for spring harvest and August 15-September 15 for fall crops. Choose heat-tolerant varieties for summer survival.
TL;DR
Phoenix's Zone 9b climate allows two distinct tomato seasons: spring planting from mid-February through March (after February 14 last frost) and fall planting in late August through September. Heat-tolerant varieties like Solanum lycopersicum 'Phoenix' and Solanum lycopersicum 'Heatmaster' are essential for summer survival, while traditional varieties thrive during cooler months.
Frequently Asked Questions
When should I start tomato seeds indoors in Phoenix?
Start spring crop seeds January 15-30 for February transplanting, and summer/fall crop seeds July 15-August 1 for late August transplanting. Phoenix's intense sun requires stronger seedlings than milder climates, so the full 6-8 week indoor growing period is essential for plant survival.
Can I grow tomatoes year-round in Phoenix?
Yes, but with significant seasonal adjustments. Spring planting (February-March) and fall planting (August-September) provide the best harvests. Summer growing requires heat-tolerant varieties like Solanum lycopersicum 'Phoenix' or Solanum lycopersicum 'Heatmaster' with shade protection. Winter growing is possible with frost protection and varieties that tolerate cooler temperatures.
What's the biggest mistake Phoenix tomato gardeners make?
Trying to grow traditional varieties on a traditional schedule. Phoenix gardeners often plant cool-season varieties like Solanum lycopersicum 'Brandywine' in March, expecting them to produce through summer. These varieties stop setting fruit once temperatures exceed 90°F, leaving gardeners disappointed. Choose varieties appropriate for each season and accept that some varieties simply won't work in desert conditions.
How do I protect tomatoes from Phoenix's intense sun?
Use 30% shade cloth during summer months (May-September) to reduce temperatures by 10-15°F while maintaining adequate light for photosynthesis. Avoid heavy pruning that removes protective leaf cover, and consider afternoon shade from tall companion plants like sunflowers. Reflective mulch helps during spring and fall by providing additional light while keeping soil cool.
Why do my tomatoes get blossom end rot in Phoenix?
Phoenix's alkaline soils (pH 7.5-8.5) bind calcium in forms plants cannot absorb, even when calcium levels appear adequate on soil tests. Additionally, inconsistent watering in desert conditions prevents calcium transport to developing fruits. Apply gypsum (calcium sulfate) to provide available calcium without raising pH further, and maintain consistent soil moisture through drip irrigation.
Which tomato varieties perform best in extreme Phoenix heat?
Solanum lycopersicum 'Phoenix' and Solanum lycopersicum 'Heatmaster' were specifically bred for desert conditions and continue producing when temperatures exceed 100°F. Solanum lycopersicum 'Roma' also tolerates heat well due to its Mediterranean origins. Cherry varieties like Solanum lycopersicum 'Surefire Red' handle heat better than large-fruited types because smaller fruits experience less water stress.
How often should I water tomatoes during Phoenix summers?
Container tomatoes need daily watering, while raised bed tomatoes typically need water every other day during peak summer (June-August). However, soil type, plant size, and exact microclimate affect needs significantly. Install a simple moisture meter to check soil moisture at 4-6 inch depth—the surface dries deceptively quickly in desert winds, but overwatering kills plants faster than underwatering in Phoenix's well-draining soils.
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Alejandro Vega
Alejandro is a landscape designer in Phoenix who focuses on low-water, desert-adapted plantings. He grew up in Tucson surrounded by Sonoran Desert plants and got frustrated watching neighbors install water-hungry lawns in a city that gets eight inches of rain a year. After earning his landscape architecture degree, he started designing residential gardens using native and desert-adapted species. Alejandro's approach is practical—he works with the climate rather than against it, using microclimates, shade structures, and efficient irrigation to create gardens that look good without draining the aquifer. He's a regular speaker at local xeriscaping workshops.
