Great question John. There are lots of ideas out there on the internet. I'm required to use .edu sources which are based on research and I'm wondering if this information could save you time and  money. 

1. Most of the purported benefits of Epsom salt, especially for home gardens, are not based on scientific evidence. As for increased productivity, there's no evidence to indicate that this is so unless your soil is deficient in magnesium. Epsom salts can be a good source of magnesium, but only use them if a soil test indicates that you have a magnesium deficiency.
2. Among the diverse plant materials that have been studied under treatment with Epsom salt, there are two commonalities: all are intensively produced crops and all were suffering from magnesium deficiency. There are no scientific articles relevant to Epsom salt use in home gardens and landscapes. We do know, however, that urban soils—including those in home gardens and landscapes—are rarely deficient in magnesium. A soil test is absolutely required before using this chemical.
3. There are many online recipes for using Epsom salt as a fertilizer, to treat physiological problems, such as blossom end rot , and to prevent transplant shock. None of these are based on science, and their use could create soil nutrient imbalances and cause substantial injury to plants.
4. Magnesium deficiencies in the home garden are most likely to occur on sandy, low pH soils. Adding Epsom salts to soil that already has sufficient magnesium can actually harm your soil and plants, such as by inhibiting calcium uptake. Spraying Epsom salt solutions on plant leaves can cause leaf scorch. Excess magnesium can increase mineral contamination in water that percolates through soil.

The best practice is to avoid adding any extra chemicals to your soil - even things that seem 'safe' - because you can easily do more harm than good.

Unless you have a magnesium deficiency in your garden, there is no need to add Epsom salts. Doing so could even be harmful to soil, plants, and water.

Consider testing your soil that has not been treated to determine if there is a magnesium deficiency.

Below is some research on the use of Epsom salt that you will find interesting. Consider a soil test using untreated soil in your garden.

https://extension.umn.edu/manage-soil-nutrients/coffee-grounds-eggshells-epsom-salts#:~:text=Adding%20Epsom%20salts%20to%20soil,water%20that%20percolates%20through%20soil.

https://pubs.extension.wsu.edu/epsom-salt-use-in-home-gardens-and-landscapes

This is a link for Franklin County, but your local Extension Office likely has test kits as well. I'm not sure of the current price, but it is usually reasonable.

https://franklin.osu.edu/program-areas/agriculture-and-natural-resources/soil-testing

This link explains how to conduct the test.

https://ohioline.osu.edu/