Why Are My Tomato Blossoms Falling Off?

I have a large (6 ft.) tomato plant, but a number of the blossoms fell off before even becoming a tomato.What is the cause and treatment? Dale H.

Answer: Since you didn’t list any other conditions, I am assuming they are getting full sun and are not suffering from any other tomato specific diseases.

Blossom drop is a fairly common problem with tomatoes, but there is no one thing that’s responsible. Here are some possible causes to help you diagnose the situation.

Temperature is the biggest factor. Tomatoes prefer a daytime high temperature above 85 degrees, and at night the temps should be between 55 and 70. There are different varieties that are more heat-tolerant: look for the phrase “heat set” on the tag or description. High night temps are troublesome for tomatoes because they don’t get to rest; if you’re having consistent high daytime and nighttime temperatures, the plant will abort setting fruit and just focus on staying alive.

Pollination is important.  If you are not seeing bees around the plant, you might have to hand pollinate or plant other blooming annuals around the plants that will attract bees and other pollinators.

Don’t over-fertilize. Many people think they should feed their plants weekly, which will ensure a nice green plant but usually few blooms or fruits. A well-tilled soil with good organic matter (compost) with a little tomato fertilizer when you plant, then a light application of balanced fertilizer when you begin to see fruit set, is all the plant needs. We recommend Espoma Tomato-tone.

Humidity outside the ideal range of 40-70 will also interrupt pollination. If humidity is too low you can water the foliage during the day; if it’s too high in your area, you’ll need to look for varieties that have been developed for high humidity climates.

Watering consistently is another important factor. Half a gallon every morning and night is just what they need.

Watch for fungal and other visible diseases prevalent in tomatoes that can inhibit blossom development.

Good luck with your tomatoes. I hope they begin to develop lots of juicy fruits.

Karen
Master Gardener