Certified GKH Gardening Expert
Epsom salt is magnesium sulfate. This is a common way to provide extra sulfur the the plant. Magnesium isn't very effective unless it is paired with calcium.
There is no harm in using this, but I prefer using dolomitic lime, and iron sulfate to achieve the same results. This mixture can be taken up faster, and condition the soil at the same time.
Here is an article for more information on epsom salt: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/epsom-salt-gardening.htm