Can you recommend some tomato varieties that will continue to produce fruit when temperatures are high?
Faced with long bouts of daytime temperatures higher than 85 degrees Fahrenheit and nights above 72 degrees, tomatoes may fail to set fruit. The plants may look dark green and vigorous — evidence that all other growing conditions are favorable — but have blossoms that dry up and fall off.
If the heat spell lasts no more than a week, the tomato plants will quickly recover. During long stretches of warm nighttime temperatures, however, the plants will stop setting, causing a subsequent gap in tomato production.
In recent years, a flood of new varieties has been bred for greater heat tolerance. Known as “heat-set” tomatoes, or “hot-set” tomatoes, some commonly grown hybrids are ‘BHN 216,’ ‘Florasette,’ ‘Florida 91,’ ‘Heatwave II,’ ‘Solar Fire,’ ‘Summer Set,’ ‘Sunchaser,’ ‘Sun Leaper,’ ‘Sunmaster,’ ‘Sun Pride’ and ‘Talladega.’ According to the Alabama Cooperative Extension System, many heat-set varieties also perform well in cool, rainy weather.
Some heirloom tomato varieties are heat-tolerant as well, and these include ‘Arkansas Traveler,’ ‘Eva Purple Ball,’ ‘Hazelfield Farm,’ ‘Homestead 24,’ ‘Illinois Beauty,’ ‘Neptune,’ ‘Ozark Pink’ and ‘Tropic.’ Additionally, some “cold-set” varieties, such as ‘Stupice,’ are all-weather standouts because they’re able to function in hot weather, too. A handful of cherry tomato varieties, such as ‘Lollipop’ and ‘Yellow Pear,’ also do well in prolonged stints of heat.
Tomato growers in the South often choose heat-tolerant tomato varieties for summer and fall production — a strategy growers farther north may want to emulate now that climate change is causing hotter summers in most regions. When growing tomatoes in hot temperatures, you can boost your success rate by planting deeper (where the soil temperatures are lower), providing afternoon shade, watering in the morning and using thick organic mulch to keep soil cool.
Learn more about heat-tolerant tomato varieties in the Alabama extension publication Blossom Drop in Tomatoes and the Louisiana extension publication Performance of Hot-Set Tomato Varieties in Louisiana. To find sources for some of the heat-set tomato varieties mentioned here, use our Seed and Plant Finder.
Photo by Tomato Growers Supply Company: 'Stupice' tomatoes thrive in cold weather and can also handle heat.