If you've grown tomatoes or peppers for more than one season, you more than likely know the feeling been waiting that first tomato to ripen, finally see it’s blushing red, and you flip it over to find a sunken, leathery patch covering half the bottom of the fruit. And if you went looking for answers, you probably found three of them repeated everywhere you turned: sprinkle in some crushed eggshells, spray on some calcium, add a scoop of Epsom salt. All three of those are extremely common advice. Two of them do close to nothing. And one of them can genuinely make the problem worse.
That problem? Blossom end rot. Today on Just Grow Something we're covering what blossom end rot really is at the cellular level, the conditions that trigger it in your garden, why the most popular home remedies for it are built on a total misunderstanding of the problem, and what the research consistently recommends instead.
Let's dig in.
University Extension and Research-Based Resources
- Utah State University Extension — Blossom End Rot (IPM Fact Sheet) https://extension.usu.edu/planthealth/ipm/notes_ag/veg-blossom-end-rot
- Purdue Extension — Blossom End Rot of Tomato Fruit (BP-13-W) https://www.extension.purdue.edu/extmedia/bp/bp-13-w.html
- University of Maryland Extension — Blossom End Rot on Vegetables https://extension.umd.edu/resource/blossom-end-rot-vegetables
- Alabama Cooperative Extension System — Blossom-End Rot in Tomatoes: Causes and Prevention (ANR-1059) https://www.aces.edu/blog/topics/lawn-garden/blossom-end-rot-in-tomatoes-causes-and-prevention/
- University of Massachusetts Amherst, Center for Agriculture, Food, and the Environment — Solanaceous: Blossom End Rot https://ag.umass.edu/vegetable/fact-sheets/solanaceous-blossom-end-rot
- Oregon State University Extension — Blossom-End Rot of Tomatoes (FS-139) https://extension.oregonstate.edu/catalog/fs-139-blossom-end-rot-tomatoes
- University of Wisconsin Horticulture Extension — Blossom End Rot https://hort.extension.wisc.edu/articles/blossom-end-rot/
- University of California Cooperative Extension, UC ANR "The Real Dirt" — Fighting Blossom End Rot https://ucanr.edu/blog/real-dirt/article/fighting-blossom-end-rot
- University of Connecticut Extension — Put an End to Blossom-End Rot: Water and Nutrient Management is Key https://homegarden.cahnr.uconn.edu/2025/06/15/blossom-end-rot/
- Clemson Cooperative Extension HGIC — Gardening Myths: Fix Blossom End Rot with Calcium Sprays https://hgic.clemson.edu/gardening-myths-fix-blossom-end-rot-with-calcium-sprays/
- North Dakota State University Extension — The Epsom Salt Myth https://www.ndsu.edu/agriculture/extension/extension-topics/gardening-and-horticulture/vegetables/epsom-salt-myth
- University of Minnesota Extension — Do Common Soil Health "Home Remedies" Work? (Coffee Grounds, Eggshells, Epsom Salts) https://extension.umn.edu/manage-soil-nutrients/coffee-grounds-eggshells-epsom-salts
- Topcu, Y., Nambeesan, S. U., & van der Knaap, E. (2022). Blossom-end rot: a century-old problem in tomato (Solanum lycopersicum L.) and other vegetables. Molecular Horticulture, 2, 1. https://doi.org/10.1186/s43897-021-00022-9
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