Blossom End Rot of Tomatoes
Blossom end rot is a common problem on tomatoes. It causes dark, leathery, sunken blotches on the bottoms of your beautiful, ripening tomato fruit. Blossom end rot is considered a nutritional disorder, since it results from a lack of calcium in growing fruits. Practically speaking, however, the cause is usually inadequate irrigation. Soil moisture is essential for roots to absorb calcium.
To avoid blossom end rot:
- Keep your tomato bed soil well limed so calcium will be present.
- Keep the plants well watered so calcium will be available. Also avoid great fluctuations in soil moisture which seem to aggravate the problem.
- Use an organic mulch around plants to help keep the soil evenly moist.
- Avoid heavy pruning or overfertilizing with nitrogen; these practices seem to make tomatoes more susceptible to blossom end rot.
- If you use black plastic mulch, make sure it has enough holes for water to penetrate. Shape your beds with concave tops before covering with plastic to avoid shedding all the water away from the plants
For more information on problems of tomatoes and other vegetables, see WSU Extension Bulletin 422, Home Gardens, or call your WSU Extension Office.
From The Gardener Vol 5, No. 2, Summer 1994.
Holly Kennell, WSU Extension Agent, King County
