My experience growing Tulips here in Southern California is limited but pre-chilling is important. Most hybrids have to have at least six weeks of chill in a refrigerator to bloom properly. Many are treated as annuals. Second year bloom on bulbs left in the ground has always been disappointing. Many large bulb suppliers will ask if you need pre-chilled bulbs when placing orders. My first season here I planted a bed of un-chilled bulbs and they all had short or weak stems. Terry Hernstrom Director Gardens & Grounds Kimberly Crest House and Gardens Redlands CA.......where scores and scores of all types of bulbs have been or are in bloom!!!