Planting Guides
When to Plant Tomatoes in Salt Lake City: Complete Guide + Best Varieties for Zone 7a
Salt Lake City, Utah
USDA Zone 7a
Last Frost: Apr 25
Last updated: October 30, 2025
Plant tomatoes in Salt Lake City from May 1-8 after the last frost (April 24). This comprehensive guide covers the best varieties for Utah's high desert climate.
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Quick Answer
Plant tomato transplants in Salt Lake City from May 1-8 after the last frost date of April 24. Choose heat-tolerant varieties like Solanum lycopersicum 'Early Girl' for best results.
TL;DR
Plant tomatoes in Salt Lake City from May 1-8 after the last frost date of April 24. Zone 7a conditions with 173 growing season days allow excellent harvests. Best varieties include Solanum lycopersicum 'Early Girl', Solanum lycopersicum 'Stupice', and Solanum lycopersicum 'Cherokee Purple' for Salt Lake City's high desert climate and temperature swings.
Frequently Asked Questions
When is the last safe date to plant tomatoes in Salt Lake City?
June 15 is the latest you should plant tomatoes in Salt Lake City to ensure harvest before the October 14 first frost. This allows approximately 120 days for varieties like Solanum lycopersicum 'Early Girl' to mature. Later plantings risk losing fruit to frost, especially for longer-season varieties like Solanum lycopersicum 'Brandywine' that need 80-100 days.
Why do my tomatoes get sunscald in Salt Lake City but not other places?
Salt Lake City's 4,226-foot elevation means 25% more intense UV radiation than sea level locations. Combined with Utah's clear, dry air that doesn't filter UV, tomato fruit literally burns when directly exposed to afternoon sun. Maintain leaf cover over developing fruit or use 30% shade cloth during the hottest part of summer. Varieties like Solanum lycopersicum 'Cherokee Purple' show better UV tolerance.
Should I grow tomatoes from seed or buy transplants in Salt Lake City?
Buy transplants for your first season while learning Salt Lake City's unique growing conditions. The 6-7 week indoor growing period requires managing Utah's intense spring sun during hardening off. Start your own seeds in subsequent years using varieties adapted to local conditions. Open-pollinated varieties like Solanum lycopersicum 'Stupice' improve when seed is saved from plants that thrive in your specific microclimate.
How do I prevent blossom end rot in Salt Lake City's alkaline soil?
Blossom end rot is extremely common here because alkaline soil (pH 7.5-8.5) interferes with calcium transport to developing fruit. Maintain consistent soil moisture with drip irrigation and heavy mulching. Don't cultivate near plants once fruiting begins—root damage disrupts calcium uptake. Add sulfur to gradually lower pH over time, making calcium more available to plants.
What's the biggest mistake new Salt Lake City tomato growers make?
Planting too early without protection from temperature swings. New gardeners see the April 24 average last frost date and plant immediately, but Salt Lake City's elevation creates dramatic day-night temperature differences that shock young plants. Wait until May 1-8 and use season extension tools like Wall O' Water or cloches for the first two weeks. This prevents the purple foliage and stunted growth that delays harvest by weeks.
Can I grow heirloom tomatoes successfully in Salt Lake City?
Yes, but choose heat-tolerant heirlooms and provide extra care. Solanum lycopersicum 'Cherokee Purple' originated in hot climates and adapts well to Utah conditions. Solanum lycopersicum 'Brandywine' is more challenging but possible with afternoon shade and excellent soil preparation. Avoid heavy pruning that exposes fruit to intense UV, and be diligent about consistent watering to prevent blossom end rot.
How late can I harvest tomatoes in Salt Lake City?
Salt Lake City's long, warm autumn allows harvesting into mid-October, often until the first hard frost around October 14. The stable fall weather and intense sun create excellent ripening conditions. Harvest mature green tomatoes before first frost—Utah's low humidity provides ideal indoor ripening conditions that can extend fresh tomatoes into December.
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Yuki Tanaka
Yuki is a landscape designer in Salt Lake City who specializes in water-wise gardens that work with Utah's dry climate and alkaline soil. She moved to Utah from Portland, Oregon—a rude awakening for someone used to gardening in rich, acidic soil with reliable rainfall. That transition taught her to rethink everything she knew about plant selection and garden design. Yuki now focuses on intermountain-adapted plantings that combine ornamental grasses, drought-tolerant perennials, and carefully chosen shrubs for year-round interest. She works with homeowners looking to reduce water use without giving up on having an attractive garden. Yuki writes with the clarity of someone who had to learn a new climate from scratch.
