Tomato Blossom Drop Caused by Extreme Heat

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Now that the High Country has arrived at peak tomato season, tomato plants in high tunnels or greenhouses may be getting too hot. Tunnels keep rain off tomato plants, reducing disease pressure, but can bring challenges of higher temperatures causing flowers to abort. Once daytime highs pass 95* Fahrenheit, flowers may start dropping from tomato vines instead of forming fruits. The problem is worse on larger, slicing varieties, and also more prevalent when night time temperatures remain above 75* Fahrenheit.

Image of tomato blossom drop

To prevent blossom drop, cool your tunnel interior to less than the mid 90’s during the day and 60’s to 70’s through the night by opening vents, running fans or placing a temporary shade cloth over the top of your tunnel. Generally, 30% shade is the most to use over summer crops such as tomatoes without causing different problems from inadequate sunlight. For more information about this and other crop management, call Cooperative Extension at 828-264-3061.