Diagnostic Guide
Why does my fruit have a dark, sunken spot on the bottom?
Check your recent watering pattern before assuming the soil is short on calcium.
Last reviewed: August 6, 2026 · Sources: Penn State Extension, University of Minnesota Extension
Start with the visible pattern
| What you see | Most likely cause | Check first |
|---|---|---|
| Dark, sunken spot at the blossom end only | Calcium uptake disruption from inconsistent watering | Review recent watering pattern |
| Damage on multiple sides of the fruit or on the stem end | Physical damage or a pest, not blossom end rot | Inspect the fruit for entry holes or insects |
Look at the fruit itself, not the soil. A dark, sunken, leathery patch specifically at the blossom end (opposite the stem) is the identifying sign.
Simple checks before you buy anything
Most garden problems have more than one possible cause. Start with the simplest explanation.
- Review whether watering has swung between very dry and very wet recently.
- Water more consistently before adding any calcium product.
- Remove affected fruit so the plant can direct energy elsewhere.
Most likely causes to check first
Calcium uptake disruption
Confidence: 80%Blossom end rot is usually caused by inconsistent watering interrupting how calcium moves into developing fruit, not a true shortage of calcium in the soil.
- Check whether watering has swung between very dry and very wet recently.
- Confirm the dark, sunken spot is on the blossom end of the fruit rather than damage from an insect or the stem end.
- Rule out an actual soil calcium deficiency with a soil test before adding calcium products.
Reference material used on this page
Penn State Extension
Watering, drainage, and root stress
Publication date: 2025
Visit sourceUniversity of Minnesota Extension
Nitrogen and iron deficiency symptoms
Publication date: 2024
Visit sourceGet the free GardenMD Quick Reference Guide
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