Native to tropical regions of South America, the tia plant (Alstroemeria), also called the Peruvian lily, thrives in warm, humid environments. Plant tia outside in USDA plant hardiness zones 8 to 11. In colder climates, keep tia plants in pots and bring them inside for the winter. Tia plants have bright, lily-like blooms that range from white and pale yellow to deep orange, plum and red. Horticulturists have developed a variety of hybrid Alstroemerias, resulting in an array of different colors.
Plant tia plants outside in the spring in an area with full-sun and loose, well-draining soil. Dig holes 8 inches deep and place one tuberous bulb in each hole. Plant nursery-started plants so the base of the stem is level with the surrounding soil. Plant container tia plants in an 8- to 10-inch pot filled with a well-draining potting soil mixture.
Keep the soil damp around potted and ground planted tias with a light application of water every other day. Use lukewarm water for potted plants during the winter to avoid shocking the roots.
Apply a balanced 10-10-10 fertilizer every other week during in the spring, summer and early fall. Discontinue using fertilizer during the winter to allow the plant to go into dormancy.
Bring potted plants indoors and put them in a sunny location before nighttime temperatures drop below freezing. Protect outside plants from abnormally cold weather with a 4-inch layer of mulch.