Spathiphyllum, or peace lilies, are herbaceous members of the family Araceae. Most Aroids are tropical plants and several, including monstera, anthurium, philodendron and caladium, are familiar indoor house plants. Peace lilies are native to the tropics of Central America but can be grown outdoors on the southern coast of Florida from Miami around the Keys to Fort Myers, provided that they are protected from temperatures below 55 degrees during the cool season. They make an impressive ground cover for shady areas.
Prepare planting areas in shady areas for ground covers in above-ground containers on shaded porches and decks or in doorways. The Mid-Florida Research and Education Center of the University of Florida recommends planting peace lilies in soil that does not fall below 65 degrees. Plant them where they can be easily protected or moved if your winter nighttime temperatures fall below 55 degrees. Plant peace lilies any time of year, as they have no dormancy requirements.
Cultivate the soil to a depth of about a foot, adding peat moss or well-rotted compost to Florida's sandy loam. Oglesby Plants International recommends an acidic soil pH of 5.8 to 6.5 for best growth and suggests a potting mix of peat, perlite and rotted bark with for container plants.
Plant spathiphyllum 24- to 36-inches apart for ground cover or on box containers with bottom drainage. Set the plants into the ground at the same height as they sit in their nursery pots.
Water spathiphyllum well as soon as they are planted and allow them to begin to droop before you water them again. Too much water can rot roots, and you'll need to observe your new plants carefully for a while to judge when they need water.
Fertilize peace lilies with a slow release garden fertilizer. Oglesby recommends working a dry slow-release formula into soil when planting or watering weekly with a liquid fertilizer with an N-P-K (Nitrogen, Phosphorus, Potassium) ratio of 3:1:2.