Epsom salt mixture for Blossom End Rot?

[Signal30]

I had a friend tell me she uses a water/epsom salt mixture to treat BER. She says it works because epsom salt has trace minerals (I assume calcium?)

Does that work?

[TZ -OH6]

No, Epsom's salt is magnesium sulfate. Magnesium helps the plant do a lot of things but avoid BER is not one of them.


Pelleted or powdered limestone/dolomite is $3-$4 a 40lb bag at many garden centers so there is no reason to use more expensive, less effective home remedies for low soil calcium.

[stella1751]

I'm going to respectfully disagree with you on this one, TZ. I've used Epsom Salts to successfully forestall future BER on pepper plants that had it. A botanist friend, a professor and weed researcher at the University of Idaho, recommended it when I had BER on my pepper plants several years ago, and I am convinced it worked.

We had a discussion on this forum last year about the causes of BER. One member said that overwatering compromised the plant's ability to uptake calcium, and that this was what caused the BER. I think adding the magnesium sulfate somehow balances the soil's mineral content, encouraging calcium uptake despite the plant's weakened condition.

I know there are many minerals and nutrients that need to be in a specific balance for optimum health and growth. For example, if a horse's vitamin E and selenium balance is off, it can cause tying up. Another one is that a young horse needs the right balance of phosphorus and calcium to maintain steady long bone growth.

Based upon this rather unscientific approach to why the Epsom Salts my friend recommended worked, I really think Epsom Salts works because it balances the soil's minerals, enhancing the availability of the calcium or something like that. I'm not certain this is why it works, but it makes sense to me

[Bobberman]

When the ph is too high alot of minerals are not availiable to plants that is why they use lime some times. I like epsom salts in small amounts at a time since it seems to work for alot of things including slugs!

[TZ -OH6]

If you run into your friend please get a reference because from what I understand of the chemical interactions (sulfate binding tightly to the calcium, calcium having higher binding strength, thus releasing magnesium etc) it is a counter intuitive result.

[hit or miss]

Here are my observations on BER in my garden. Last year I made the switch to all natural gardening with no manmade chemical fertilizers and such. I have been adding compost and using some natural sources of NPK such as fish emulsion. I dug a couple of new beds also last year.

Last year I had great tomatos with almost no BER. In the past we had to pitch many of the first fruits, enough to tick me off!

This year I have an old bed and a new bed planted with 'maters. In the old bed, no BER. The new bed, suffering some losses. I'm convinced the compost and natural additives I've been using are working the trick!

[stella1751]

If you run into your friend please get a reference because from what I understand of the chemical interactions (sulfate binding tightly to the calcium, calcium having higher binding strength, thus releasing magnesium etc) it is a counter intuitive result.

Odds are against me running into this friend. I haven't seen him since I left Cheyenne for Casper in 2006. However, I jetted him off an email at his university address. He does research over the summer, so I believe he checks his email. Based upon what you wrote, maybe it's not the magnesium that enhances availability but the sulfate.

[mmmfloorpie]

I've used epsom salts for the past few years now and I've never had a significant BER problem. The first years when I gardened and I didn't use it, I did notice problems.

[TZ -OH6]

Thanks for emailing him. I appreciate any extra info you can dig up.

I ran across a post about magnesium deficient leaves on another forum from one knowlegable tomato grower who does have to use magnesium on a regular basis, but not for BER. he lives in an area of the country that is rare in that it has low magnesium. In that case epsomes salts would boost overall plant health and help things out, but with normal soil ean exess of magnesium could cause problems.

Here is something from University of Illinois

Losses from blossom-end rot increase when the soil contains an excess of total soluble salts in relation to soluble calcium salts. An excess of soluble ammonium, potassium, magnesium, or sodium salts reduces calcium uptake by the plant.

https://ipm.illinois.edu/diseases/series900/rpd906/index.html

This is also good, but less specific to BER

https://www.puyallup.wsu.edu/~Linda%20Chalker-Scott/Horticultural%20Myths_files/Myths/Epsom%20salts.pdf

Note that both mention problems from high potassium, which is common from both organic and inorganic fertilization methods.