Hey Fred,
I read this awhile ago on the website below.
http://www.herbs2000.com/flowe...
Many growers, including some leading hybridizers, also add sewage sludge. This contains magnesium which helps to enhance the near-blue effect in flower colors and gives the foliage a good color. Epsom Salts (magnesium sulphate) has the same effect. It can be used at the rate of 3 tablespoons of crystals per gallon of water and must be applied in solution only. Its overuse over a prolonged period may make the soil too acid for daylilies and can also lead to a build-up of salt. Lime can help remedy acidity.
I read on other sites to dissolve the salt in hot water first.
If I may ask, what's your purpose for the Epsom salt?
