Epsom salts prevent blossom-end rot.
Epsom salts won't stop blossom-end rot. BER is a calcium-transport problem caused by uneven watering. A magnesium shortage doesn't cause it, and Epsom salts add magnesium, not calcium. Water evenly, mulch to buffer soil moisture, and soil-test before adding anything.
What is actually known
Blossom end rot is a localized calcium shortage in the fruit, driven by uneven water uptake. Calcium rides the transpiration stream, so erratic watering starves the fruit tip even when soil calcium is adequate. It is not a magnesium deficiency. Epsom salts add magnesium, not calcium, and the calcium is usually already in the soil, so they do nothing for BER. The levers are even watering and mulch; get a soil test before adding any nutrient.
The evidence
Evidence: checked against 1 source in the research-based literature.
The source
This is a problem born of calcium deficiency, most often the result of erratic watering
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Milpa Gardens. “Epsom salts prevent blossom-end rot.” Evidence grade: Refuted. https://milpa.garden/beliefs/epsom-salts-blossom-end-rot/
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