Flowering is related to the length of light during the day and night temperatures. The temperature range for flower bud development is between 50-60°F for a period of at least six weeks. The plant will need at least 12 hours of total darkness each night for 8-10 weeks or until you start to see buds form. Usually a closet, basement or garage is a good location, and the plant can be covered with a dark sheet of cloth. For holiday blooms, this needs to be done in late September to mid-October.