It's very easy to apply. I do mix it by the water can load since I use rain barrels. If you are a rain barrel user you can also add it to a full barrel, throw in a pump and spray the garden. Fish emulsion used in slightly weaker than recommended forms (since it is getting hot out now) can be applied as a foliar feed early in the morning to the entire garden. I would not add epsom salts to anything but roses and brugmansia and things that need the extra magnesium and only do that once a year or so.
You can also add your fish emulsion mix to a back pack or garden sprayer and spray away...if you use a hose, you can put it in a hose end sprayer and set the sprayer to mix two tablespoons of the fish emulsion to three gallons of water.
Stinky, but it works!! It's my fave!
GGG

I've been using it on my roses this year. I mix it in with the fungicide with my backpack sprayer. Don't use to much or you'll get complaints! LOL.