The recent rollercoaster of temperatures can cause some pollination delays and setting and ripening issues with tomatoes.
Temperatures that remain above 75 degrees F at night and day temperatures above 95 degrees F with dry, hot winds will cause poor fruit set on tomatoes though cherry tomatoes seem to be more heat tolerant than slicers.
High temperatures interfere with pollen viability and/or cause excessive style growth leading to a lack of pollination. Tomatoes that have already formed are not affected.
It usually takes about 3 weeks for tomato flowers to develop into fruit about the size of golf balls. Growth then becomes more rapid with the mature size being reached in an additional three to six weeks. A few more days are then needed to change color.
Gardeners might want to try some of the "heat-set" slicing tomatoes varieties such as Florida 91, Sun Leaper and Sun Master that will set fruit at higher temperatures, a difference of only 2 to 3 degrees. Cooler temperatures will allow flowers to resume fruit set.
The hot weather we have had recently not only interferes with flower pollination, but also can affect how quickly fruit matures. The best temperature for tomato growth and fruit development is 85 to 90F. When temperatures exceed 100 degrees, the plant goes into survival mode and concentrates on moving water. Fruit development slows to a crawl. When temperatures moderate, even to the low to mid 90s, the fruit will ripen more quickly.
Tomato color can also be affected by heat. When temperatures rise above 95 degrees F, red pigments don't form properly though the orange and yellow pigments do. This results in orange fruit. This doesn't affect the edibility of the tomato, but often gardeners want that deep red color back.
So, can we do anything to help our tomatoes ripen and have good color during extreme heat? Sure, there is. We can pick tomatoes in the "breaker" stage. Breaker stage tomatoes are those that have started to turn color.
At this point, the tomato has cut itself off from the vine and nothing will be gained by keeping it on the plant. If tomatoes are picked at this stage and brought into an air-conditioned house, they will ripen more quickly and develop a good, red color. A temperature of 75 to 85 degrees F will work well.
For more information on growing tomatoes, contact the Ford County Extension Office or visit us online at www.ford.ksu.edu. Have a great weekend and get out and enjoy the first weekend of Dodge City Days!