The bottoms of my tomatoes look rotten

by Janis
(Marysville, Calif.)

Q. The bottoms of my tomatoes look rotten! What is this and what should I do?

A. When the bottom side of the tomato (either a green or ripened one) develops a sunken, dark spot or rot, it has developed blossom end rot (BER). Blossom end rot is caused by a calcium imbalance.

Calcium helps bind cells together in tomatoes. Tomatoes absorb it through water. But calcium is s-l-o-w moving! If a tomato is stressed or if it grows quickly, then calcium can't get to tissues fast enough, especially those on the bottom of the fruit furthest away from the stem. So tissues break down. Thus the rotted spots on the end of the fruit.

You can eat tomatoes with BER. Simply cut out damaged parts.

As far as what to do: the best treatment is prevention. (Learn more about how to prevent blossom end rot on tomatoes.)

But now that your tomatoes already have BER, you can treat them by applying calcium immediately. You can use these natural products specifically developed to treat, prevent, and slow blossom end rot in tomatoes: Enz-Rot Blossom End Rot (a concentrate that can make up to 8 gallons) and Tomato Rot-Stop (in a ready-to-use spray bottle.) Follow package directions for application. Or mix 1 tablespoon calcium chloride (sold commercially for other uses as de-icing salt or DampRid® Closet Freshener) in one gallon of water. Spray 2-3 times a week until blossom end rot is under control. Or spray plants with milk.

There are other measures you can take. Pick affected and unaffected fruit on BER plants to reduce stress on the plant. Make sure you keep your tomatoes on a regular watering and fertilization schedule.

Plants often outgrow BER after mid-season. So take heart - you can still grow healthy tomatoes this year!

Read about blossom end rot in more detail.

Good Luck and Happy Gardening!
Your friends at Tomato Dirt