Mix 1 tablespoon of Epsom Salts into 1 gallon of water in a jug or pitcher. Shake or stir the mixture thoroughly. Apply this solution to your peace lily every 4 to 6 weeks in place of a water application. Shake the container before each use.
If you have a fish tank, save the water from a tank cleaning in a clean jug. Shake the water and apply to the base of the peace lily every month in place of a water application. This homemade fertilizer will provide much-needed nitrogen to your plant.
Mix 1 tablespoon of white vinegar into 1 gallon of water in a jug or pitcher. Shake or stir the mixture and apply to your peace lily once every three months in place of an alternate monthly feeding. Vinegar contains acetic acid, and will increase the acidity of the soil slightly.
Rinse out empty milk cartons and apply it to the base of your peace lily. Milk contains nitrogen, phosphorous and potassium -- all components of a basic commercial fertilizer. Use the rinse water from apple or orange juice containers in the same manner to provide a potassium boost to your plant.