Supplies magnesium, and "greens up" foliage, most common reasons. Probably find lots info in search, "epson salt".

After posting above, did my own search. One of the replies went like "its epsoM, epsoN is a printer company owned by Seiko." Now I will always remember to spell it correctly. (but epsoN works on search.)

Mix 1 tablespoon/gallon warm water. Apply around base of plant spring and fall. Can brighten colors also.

Search for Hooker formula.
Ed

Thanks a lot, I will try it and pass it on to my mom.

Well, yes, according to the industry council it's 'epsom salt'. They have a nice write up on garden use.

It is a catalyst for many plant functions. In addition to increasing production of chloriphyl, it is commonly used to promote bloom in roses, vegetables, orchids and epiphelium. It improves the plants ability to process other nutrients like nitrogen and phosphorus.

I used it this year on an Easter cactus that I've never been able to bloom. It set bud w/in 1 week of applying epsom salt.

Here is a link that might be useful: epsom salt industry council