I bet you have had one of these in home over the years! Christmas Cactus are very long-lived classic houseplants - and often passed down through family or as gift to young adults moving into a new apartment or first home. Not to mention they are popular in offices and other public spaces! All this because Christmas Cactus can be very good companions... and spectacular when in bloom.
Here are some tips for best success growing and getting your Christmas Cactus to bloom:
1) Christmas Cactus require contrasting seasons in order to bloom. These are tropical cacti that have evolved with a distinct wet and dry season. Unlike desert cacti, that generally thrive under arid conditions, Christmas Cactus require regular deep watering from spring through early fall. If December blooms are the goal, watering should be reduced starting in September and skipped entirely for the month of November!
Speaking of watering: ensure your Christmas Cactus is growing in a pot with drainage and that it never sits in standing water. The rule of thumb for Christmas Cactus is to never water until the top 1/3 of the soil has dried out from the last watering.
2) Christmas Cactus are affected by light/dark cycles. These plants do not naturally want to bloom when daylight hours are increasing or peaking. Instead Christmas Cactus are sensitive to the declining daylight hours of fall. Fine tuning of bloom period can be achieved by placing Christmas Cactus into total darkness for 12 hours per day (for December blooms start this in early November; once buds are visible move to normal conditions).
3) Christmas Cactus require cool temperatures to set flowers. The ideal temperature for getting Christmas Cactus to bloom is between 10-12°C but certainly less than 18°C. Try a big patio door or bay window for the cactus - these are inevitably cooler than your cozy areas indoors.
4) Christmas Cactus require bright but diffused light. These plants have sensitive foliage that can sunburn if exposed to excessive direct sunlight. They do require brightness so south windows are great - just make use of drapes to break the sun (or pull your plant back from the window). Also be careful if you ever put your Christmas Cactus outdoors; this is a common cause of sun damage. The plants do appreciate the fresh air but a part-shade location is recommended.
5) Feed your Christmas Cactus in winter/spring/summer but not in October/November/December. The best fertilizer is a general purpose organic such as Evolve All Purpose 3-1-2. During the active growing season you should feed Christmas Cactus monthly; this ensures it has the vitality required to set December flowers. The occasional spring/summer application of Epsom Salts is helpful as Christmas Cactus require lots of magnesium.
6) Trim your Christmas Cactus after flowering. Once the blooms are faded/dropped the plant benefits significantly from a good pruning. Remove the flowering stem tips using scissors. This promotes branching and increased future flowering..
7) Christmas Cactus love to be pot bound. It is important to avoid having too much soil around the roots (it is an epiphyte). This is great if you are into low maintenance! They can be repotted every few years... and eventually get quite big. Very large Christmas Cactus can be gently divided (to invigorate them) if they show signs of decline.
I've had quite a few people ask about specific problems with their Christmas Cactus. The top two of these problems are: the leaves are limp or the leaves are pale. Limp foliage is a sign of either over watering or exposure to excessively cold temperatures. Pale foliage reflects the need for more regular feeding.
Hopefully these tips can help you enjoy your Christmas Cactus to the fullest!