: Tomatoes need a pH of around 6.5 to properly absorb calcium.
: Over-fertilizing with high-nitrogen food can make the plant grow so fast that the calcium can't keep up. teenage black toes
Because tomatoes are mostly water, they need a constant stream of calcium to build their cell walls. If that stream is interrupted while the fruit is growing (the "teenage" stage), the cells at the very bottom (the blossom end) literally collapse, leading to: : Tomatoes need a pH of around 6
Despite the "black" appearance, this isn't usually caused by a fungus or a pest. Instead, it is a caused by a calcium deficiency within the fruit itself. leading to: Despite the "black" appearance