By Azura · Updated June 2026 · Raised Garden Hub is reader-supported. When you buy through links on our site, we may earn an affiliate commission at no extra cost to you.
Blossom end rot is the dark, sunken spot on the bottom of a tomato — and it’s a watering problem, not a disease. It happens when the plant can’t move enough calcium to the fruit, almost always because the soil moisture is swinging between wet and dry. The fix is consistent watering, not more calcium.
What it looks like
A water-soaked spot on the blossom (bottom) end of the fruit that turns brown-black, sunken, and leathery. It also affects peppers, squash, and eggplant.
The real cause: inconsistent watering
Most soil has plenty of calcium. The problem is delivery — when the plant dries out then gets flooded, it can’t move calcium to the fast-growing fruit in time. Result: the blossom end starves.
How to fix it
- Water deeply and consistently — the single most important step. Aim for even soil moisture, not feast-or-famine. A 12-inch-plus raised bed holds moisture better.
- Mulch 2–3 inches to buffer soil moisture (see keeping beds healthy).
- Don’t over-fertilize with nitrogen — fast leafy growth pulls calcium away from fruit.
- Remove affected fruit so the plant redirects energy to healthy ones.
- Skip the “add calcium” shortcuts — eggshells and sprays rarely help if watering is the issue.
Will my plant recover?
Yes. Blossom end rot affects the current fruit, not the plant. Once your watering is steady, new tomatoes form normally. And you can still eat affected fruit — just cut off the bad end.
It’s the same fix that prevents most tomato, pepper, and zucchini problems: consistent water in free-draining raised-bed soil.
Frequently asked questions
What causes blossom end rot?
A calcium deficiency in the developing fruit, almost always caused by inconsistent watering rather than a lack of calcium in the soil. When the plant can't move calcium to the fruit fast enough, the bottom turns into a dark, sunken, leathery spot.
How do I fix blossom end rot?
Water deeply and consistently — that's the real fix. Mulch to keep soil moisture even, avoid over-fertilizing with nitrogen, and remove affected fruit so the plant focuses energy elsewhere. New fruit will form normally once watering is steady.
Is blossom end rot a disease?
No — it's a physiological disorder, not a fungus or virus, so it doesn't spread plant to plant. You can't catch it or treat it with fungicide; it's fixed by consistent watering.
Can I eat tomatoes with blossom end rot?
Yes — just cut off the affected bottom. The rest of the tomato is safe to eat.