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UC Master Gardeners of San Mateo & San Francisco Counties
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Blossom End Rot on Tomatoes?

Pile of tomatoes

As you’re enjoying the tomatoes from your garden, have you noticed some with brown areas on the bottom end? Blossom end rot is caused by a lack of calcium in the plant, most likely due to irregular watering (it’s not caused by a disease). To control the problem, maintain even moisture in your soil, apply mulch to conserve moisture and avoid over-fertilizing with nitrogen. For more information, click here.