The mild winters that are so comfortable for us are not so desirable to tulip bulbs, which need to be chilled to perform as perennials. Consequently, they behave as brief season annuals locally. The most popular varieties have simple single flowers in white, yellow, pink, red, purple or pinkish orange. Double tulips are rather ruffled. Parrot tulips are larger and even more ruffled. As the names imply, lily-flowered tulips are shaped like small lilies, with pointy flared petals; and fringed tulips have finely serrate petals. Tulips stand between half a foot to two feet tall. Early types are already finished blooming. Late types, particularly if planted late, may bloom as late as early May.