Does anyone put Epsom salt in the hole when they plant tomatoes
I use a little, although it may not be necessary. Epsom salt is magnesium sulfate. Magnesium is an essential nutrient but not much is needed and most soils have enough.
If you pop on over to the Growing Tomatoes forum here (linked as a related forum on this one's front page) you'll find many discussions about the use of epsom salts - when, how, and how much.
Adding epsom salts when planting tomatoes is a widely held "prescription for success." Unfortunately, it doesn't do anything unless the soil needs magnesium.
Only a professional soil test can determine if that's so.
The first couple of years I grew tomatoes I had a lot of blossom end rot. Then I read some posts about calcium uptake & magnesium on the tomato forum. Ever since, I've added a handful of bonemeal & a handful of dried crushed egg shells into the hole. I stick the tomato plant in pretty deep with just a few inches of foliage above ground. I backfill, adding a handful of epsom salts along with the soil. Sometimes I throw a few Tums into the hole as well, but only if I'm feeling nervous... Occasionally one or two of the first tomatoes will have BER, but nothing like before.
What if the soil needs sulfur? Or to rephrase, will this chemical lower or raise the pH?