By Katie Markheim, Nebraska Extension Master Gardener
Dear Master Gardener, what are the dark, soft spots on the bottom of my tomatoes?
Blossom end rot is a very common problem on green and ripe tomatoes caused by a calcium deficiency. It first appears as a sunken, brownish black spot 1⁄2 to 1 inch in diameter on the blossom end of the fruit. It occurs in rapidly developing fruit during periods of hot, dry weather.
To prevent, maintain a steady rate of plant growth without stress. This includes watering consistently, mulching to conserve soil moisture, monitoring nitrogen fertilizer applications, properly staking plants, and sanitizing pruning equipment after each use. If blossom end rot occurs, remove the affected fruit.