Tomatoes Dropping Flowers

A Beefsteak tomato at Bluebird Gardens with blossom drop from record hot temperatures.

A Beefsteak tomato at Bluebird Gardens with blossom drop from record hot temperatures.

Tomatoes Dropping Flowers

When I dream of my summer garden, or see a summer garden quilt throw, I look for tomatoes first. If there is one vegetable that represents summer vegetable gardening, it's these wonderful fruits that add color, flavor and good antioxidants to our salads and other food.

Our local newspaper asked me to call someone about their tomatoes. The gentleman was polite on the phone but clearly frustrated. His 6-foot high tomatoes in barrels at a 7 Ph level where flowering but then the flowers were falling off. He said something similar had happened to his potatoes last year.

Several Possible Factors

There are several factors that cause tomatoes to drop their flowers, starting with the impact of record high temperatures. Tomatoes, like most flowering plants, go into survival mode if temperatures are above 90F for five or more days in a row. We just set record temperatures for June in Missouri so the record hot temperatures may be a leading culprit.

Plant survival mode means most systems are shut down, including pollen production. It’s why a plant may seem to die in hot weather and yet reappear the following year. As long as the roots can pull through, most plants will survive.

High Temperatures and High Humidity

Tied to temperature is high humidity. Humidity that is too high prevents pollen from sticking to the stigma once it is released. Without pollen, there are no pollinators and without pollinators, there are no flowers that produce tomatoes.

Leading tomato pollinators are native bees, especially bumble bees. These little hoodlums of the bee world literally shake the plant, releasing pollen all over the stigma and themselves. When high temperatures shut down pollen production, they also put bees out of business.

Next, two more factors that can impact successful tomato growing. Any guesses what they might be?