After planting the bulbs in containers of moist potting soil, chill them for the number of weeks listed. The chilling temperature can start at about 50 degrees to encourage rapid root growth, but by the third or fourth week of chilling, the temperature should stay between 35 to 45 degrees. Don't let the temperature drop below freezing, or the bulbs could be damaged. Check the pots monthly to make sure the soil is moist and to look for root growth. When roots envelop the soil ball and emerge from the drainage hole, and green shoots poke through the soil, the bulbs are ready to bloom. At that time the potted bulbs can be brought to a warm, bright room. From the day the pots are removed from cold storage, it will take two to three weeks for the bulbs to bloom.
Download a list of great bulbs for forcing that includes how many weeks bulbs need to chill and how many weeks until they bloom. (Downloading requires Adobe Acrobat software.)