Alstroemeria is a perennial plant also known as Lily of the Incas or Peruvian lily. Although all parts of the plant are poisonous and cause skin irritation, they are often grown for use as a colorful addition to cut flower arrangements. An alstroemeria plant may grow as tall as 48 inches (120 cm), and its flowers, which appear around late spring, range in color from white, pink and salmon to bright orange, red and purple. Alstroemeria is considered hardy in temperatures as low as 23 degrees Fahrenheit (-5 C) and prefers a protective mulch or afternoon shade in extremely hot temperatures. Plant alstroemeria seeds in the fall, when temperatures do not exceed 68 degrees Fahrenheit (20 C) daily and range between 40 and 50 degrees Fahrenheit (4 to 10 C) at night. Learning the proper manner of how to grow alstroemeria is the key component to a beautiful garden or supply of flowers for a cut arrangement.