Epsom salts help nourish your houseplants by providing magnesium--the building block of leaves' green chlorophyll pigment. Also known as magnesium sulfate, Epsom salts dissolve readily in water and absorb into roots when soaked into the soil. Being organic, these nonsalt crystals do not harm plants, even when you accidentally add a bit too much when making a dosage.
Fill your watering can or container with 1 gallon of water. Allow the filled container to rest for at least an hour to warm to room temperature and allow any chlorine additives to evaporate.
Measure 1 tsp. of Epsom salts, add it to the water, and stir it in.
Water your houseplants with the solution, following the same procedure you've always done when watering.
Repeat the application of the Epsom salts solution to your houseplants again in three or four weeks. Use regular water for any watering needed between times.