Blossom End Rot in Tomatoes by Stan Ames

Are some or all of your recently set tomatoes, squash, watermelons, peppers or eggplant developing dark, leathery features on their bottoms?

With the abnormal amounts of rain we have enjoyed we need to be alert to this condition and take steps to prevent its onset.  Once a fruit has been damaged it cannot be cured!

The technical term for this condition is “Blossom End Rot” and in some areas it is just referred to as “BER”. This condition is a result of the plant’s need for calcium not being satisfied.


Plantalk Colorado’s publication No. 1471 lists six major causes for this condition and we, in Jefferson County, have experienced three of those causes this year.

1. Sharp changes in temperature from cool to hot weather.
2. Extreme temperature fluctuation.
3. Waterlogged soils from too much rain or excessive watering.

Prevention steps include ensuring your plants are in well-drained soil, enjoy an even supply of water (mulching helps), taking care not to cause root damage when weeding and avoiding the use of high nitrogen content fertilizers. Keep that lawn fertilizer away from your plants!

The complete publication can be seen on the web at www.ext.colostate.edu/ptlk/1471.
Additional information can be found in the Colorado State Extension website www.ext.colostate.edu by searching for: Recognizing Tomato Problems, Tomato diseases, and Tomatoes for the home Gardens.

Don’t forget the Extension website listed above is an outstanding source of information on most gardening issues.  Make it your first source of information! Or call the Jefferson County CSU Extension directly at 303-271-6620.