Epsom Salt — Great For Tired Feet — Not So Great In The Garden
Another Myth That Never Seems To Die
💬 Opinion | by Guy Saldiveri | May 31, 2026
The Truth Up Front:
Folklore Wisdom: Epsom salt is a cure-all for ALL your plant maladies.
Gardening Fact: Unless you have a magnesium deficiency in the soil — which is uncommon in most home gardens — adding Epsom salt will most likely do more damage than good.
Epsom salt is magnesium sulfate — an inorganic salt — and has been used in both the medical and agricultural communities for a very long time.
Medical: Used in warm baths to soothe sore muscles, reduce inflammation, and relieve stress. It is also used medically as a laxative or via IV to treat conditions like preeclampsia and severe asthma.
Agriculture: Used as a soil amendment to correct magnesium or sulfur deficiencies in crops, though, as noted, it is only beneficial if a true deficiency exists.
What happens if you don't have a deficiency?
Magnesium, alongside calcium, is one of the secondary nutrients that plants need to maintain health and produce fruit. Plants need far less of it than the big three nutrients — nitrogen, phosphorus, and potassium.
Magnesium competes with calcium and potassium uptake in plants.
I find it ironic that folks recommend using Epsom salt to cure blossom end rot. BER is a calcium deficiency caused by numerous things, but adding Epsom salt makes it harder for the plant to absorb calcium even if there is plenty to go around.
It can help create the very problem people are trying to prevent. How's that for sowing some real truth…
So Why Do So Many Garden Doctors Prescribe It?
On this one, you can probably take your pick here:
• It looks like it works — plants green up for unrelated reasons, and folks credit the salt
• It’s cheap, easy, and feels like garden magic — sprinkle, stir, and hope
• Correlation confused with causation — the oldest trap in the garden
• Because grandma did it for 50 years — tradition is a powerful fertilizer
In my blossom end rot post, I talk about how the first batch of tomatoes often comes out with a case of BER. The second batch is usually much better because the roots finally catch up to the rest of the plant’s growth. That’s normal physiology.
But here’s where the myth grabs hold:
People see that first batch, panic, shout “BER!”, and then toss in calcium, Epsom salt, crushed Tums, eggshells, or whatever the internet told them.
Then the second batch comes out clean, and they think:
“See? It worked!”
But that’s correlation vs. causation at its finest.
The second batch would have most likely come out clean even if they had done absolutely nothing at all.
And as I’ve already pointed out, adding Epsom salt can actually perpetuate the problem by making calcium uptake harder, not easier.
That’s the part nobody wants to hear — the “cure” they swear by is often the thing making the problem worse.
There are a few more problems associated with using Epsom salt, such as runoff and groundwater contamination, but we can leave those for another time.
For the time being, here's a list of facts to keep in mind the next time you reach for that bag of salt:
- Make plants bushier
- Increase flowering
- Increase fruit production
- Prevent blossom end rot (it can actually cause it)
- Repel pests
- Improve germination rates
- Replace fertilizer
In a nutshell:
It does far less good than people profess — and possibly more harm than they realize. Epsom salt is great for its intended purpose, but for the most part, it’s better left to the foot bath than the tomato plant. If your soil doesn't need magnesium, Epsom salt isn't a remedy — it's just another thing you're adding because someone on the internet said it worked.
If you appreciate these straight‑shooting, porch‑talk opinions, you’re welcome to follow along on the left — there’s more to come, no pressure at all, just honest company and honest talk. 🙃
Happy Gardening 🌱
Truth.
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