Do you have healthy looking tomato plants with no fruit? Temperatures below 55°F or above 90°F can cause tomato flowers to fall off or fail to set fruit; too much shade can also result in no fruit. Lush dark green abundant leaves with no flowers may be a result of too much nitrogen.
Good fruit production with poor color development is also linked to temperatures. Optimum color occurs between 65 and 70°F. Summer temperatures that are too high speed up ripening and produce fruits that are more orange than red. Prolonged cool temperatures slow down ripening so fruit stays green. White, yellow, or leathery brown patches on the side of the fruit are symptoms of sunscald, the sudden exposure to direct sunlight in hot, dry weather.
It’s easy to assume that some sort of pest is the cause of most problems but that’s not always the case. For example, circular, concentric, or radial cracks from the stem end of the fruit appear when there are significant differences between day and night temperatures, periods of rapid growth during high temperatures or wide fluctuations in soil moisture. Catfacing (misshapen or malformed fruit at the blossom end) causes the fruit to pucker and have deep crevices and can show up after abnormally cool or hot conditions. A small water-soaked spot near the blossom end of the fruit (blossom end rot), may be apparent when calcium is not readily available to developing fruit due to fluctuations in soil moisture.
While there’s not much you can do about the weather, you can continue to provide your plants with plenty of sun and adequate, consistent water. Protect precious fruit on particularly hot days with shade cloth or screening material and avoid over-pruning the plants, allowing leaf cover to shield fruit.
Learn more about growing great tomatoes here. Have other issues with your garden? Check out our Plant Health Problems page.