If you are having the same amount of luck that I am having attempting to produce great tasting tomatoes this summer, I apologize. I have received numerous calls and complaints this growing season on the lack of productivity growers are experiencing. The two complaints are 1. My tomatoes won’t set any fruit or 2. The fruit has set, the tomatoes won’t turn red or grow any larger. Heat is the explanation on why fruit stops ripening, or won’t produce fruit at all.
Tomatoes stop making the pigments carotene and lycopene at temperatures higher than 85 degrees. Even though the tomatoes are called ‘full sun’ plants, the roots have to be cooler than 80 degrees and the fruit has to be shaded by foliage to keep it cool enough to ripen fully. You can pick green tomatoes when the blossom end is one-third pink and ripen them in the kitchen window. Tomato and bell pepper color, flavor, plant growth and fruit production are optimal when the daily temperature are 70-75 degrees, with nighttime temperatures 60-65F. High temperatures, specifically anything above 85F during bloom and ripening periods, will result not only in reduced fruit set, but fruit flavor, texture, and color will be directly affected.
This ‘tomato time-out’ is mainly due to the plant using most of its resources, like water and nutrients, in addition to its manufactured photosynthetic products, to simply survive temperature extremes. More resources maybe partitioned to produce more roots in an attempt to assess more water which causes the plant to suddenly cease to grow. Remember, the plants are attempting to sustain all of their physiological processes, like cooling the leaf tissue, and continue to grow in order to produce new blooms, foliage, and ripening fruit all at the same time! This requires a huge amount of plant resource and energy!
So if you are experiencing lack of tomato plant ripening or setting fruit, don’t stress, we are all experiencing the same thing! All we can do is continue to water the plants and wait until cooler temperatures come. If you have any questions regarding tomatoes or anything AG related in Jasper County, please feel free to call the UGA Jasper County Extension Office at 706-468-6479.