Tomato Plants Flowering but are not Fruiting

Q:  My tomato plants are blooming but not setting fruit.  What’s up with that?

A:  Tomato plants that bloom without setting fruit is mostly due to extreme temperatures, poor pollination, or too much nitrogen. 

This time of year I suspect the culprit is high temperatures. Daytime highs above 90°F can make the pollen clump or die resulting in no pollination and no fruit setting. Using a Tomato Set or Fruit Set spray on the flowers every few days will result in fruit set without pollination and is completely natural.  

Tomatoes are self-pollinating, so lack of bees is not the problem. But the flowers do need wind or physical shakes to move the pollen into position to pollinate the flowers. Lack of air movement in quiet or sheltered spots stops the process. You can fix this by physically shaking the plants daily, or using a leaf blower on a low setting to jostle the plants.

Too much nitrogen: High nitrogen feeds lush green leaves instead of flowers and fruit.  If you are applying a fertilizer with a high nitrogen content (the first number in the analysis), switch to a low nitrogen, high phosphorus feed. The organic Espoma Tomato Tone feed works great. It also contains extra calcium to help prevent blossom end rot.  

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Read our Q & As with Keith Funk answering common Colorado gardening questions here. See his website: gardenwiseguy.com and hear him on the Garden Wise Radio Show