Coaxing Your Christmas Cactus to Bloom
Grower Tip: Christmas cactus have internal calendars that tell them when to bloom and you can't change it. Your goal is to give the plant the right growing conditions during Sept-Nov that will trigger blooms.
The Key to Getting Your Christmas Cactus to Bloom is Cool temperatures at night.
Starting in September or October, move your plant to a room where temperatures drop to around 50 degrees at night. If you're growing outdoors, simply leave your plants outside until evening temperatures drop into the 50 degree range. Don't expose them to freezing temperatures however.
This may not be as difficut as it sounds. Choose a window where you can close the heat vents. When the weather turns cold outdoors, the windowsill can be 15-20 degrees cooler than the rest of the room. (A Hi/Lo Thermomter is a good way to measure this.)
Light: Continue with bright light and some sun. Try to keep plants away from artificial lights in the evening because that can interfere with setting blooms. Commercial growers go to great lengths to keep plants totally dark for at least 12 hours to insure blooming.
Water: Be stingy with the water. With hydroponics that means pouring water over the pebbles until the water gauge moves, then stop. Lift inner pot to make sure everything is totally dry before rewatering - usually about 2 weeks. Skip nutrients altogether during this period.
When the first blooms appear move plant to wherever it looks its best.
After the blooming season is over, give your plant a resting period of a month or so. Put it in a cool room and water it just enough to avoid dehydration. Simply wet the pebbles every week or so. Don't worry if your plant loses a few leaves and appears weak during this rest period.
After a month, start the new growing season by increasing water and nutrients.
