Peace lilies can be planted outside only in climates that do not freeze, because extreme cold kills the plants. For cold climates that freeze, peace lilies grow well in containers that stay inside during winter and outside during summer. Peace lilies that are placed outside require a shady location.
The appropriate soil for peace lilies grown in containers is an equal mixture of sand, loam and peat moss. The soil needs regular moisture from distilled water or tap water that sits overnight to allow the chlorine to dissipate. Large peace lilies that outgrow their pots can be divided and re-potted in fresh soil.