by Donna Hull
It’s the time of year to enjoy a few holiday-inspired plants. The garden centers are filled with poinsettias and fresh pine, but don’t forget to invite another beauty into your home – the holiday cactus.
There are three holiday cacti – the Thanksgiving cactus, Christmas cactus, and Easter cactus. The first two, which are the most commonly bought and enjoyed by gardeners, are separate species of the genus Schlumbergera which bloom in November and December, respectively. And while they are members of the Family Cactaceae, these are not the cacti we think of from dry regions. Schlumbergera are native to the higher altitudes of tropical rainforests in Brazil. They are epiphytes, meaning they grow on trees (and sometimes out of rock fractures) in the rainforest, where they receive consistent rainfall and indirect light. The temperatures are moderate, the soil rich in organic matter. Not your desert cactus at all!
Because your home is likely not a perfect substitute for a tropical rainforest (nor would you want it to be!), a little coaxing must be done to get our holiday cactus to bloom. In its native environment, Schlumbergera usually blooms at the end of the rainy season, when temperatures and light reach the appropriate levels to set off the formation of buds. Since you are likely aiming for flowering during the holidays, begin the forcing process 6-8 weeks before your preferred bloom time. The forcing process focuses on two growing factors: light and temperature. Schlumbergera will begin to form flower buds through a reduction in temperature and an increase in the hours of darkness that they are exposed to. In North Texas, this is a good time to set the plant outdoors (if possible), exposing the plant to 50-55°F with 2-6 hours of complete darkness (no artificial or natural light) or 60-65°F with 12 hours of complete darkness. At 70°F the plant will need 15 hours of darkness. Do not fertilize during this period, and only water when dry to the touch. After the buds have formed, the plant can stay in 65-70 °F, and resume regular watering (keeping the plant moist, not water soaked) and light. Be sure to bring them inside if the temperatures fall below 50°F – they like it cool, but not too cold! If all goes well, you will be rewarded with 6-8 weeks of colorful holiday cactus blooms.
After the Bloom Wears Off
Once they have finished blooming, Schlumbergera will need (and deserve) a resting period, typically January through March. Keep the plants in indirect light. Water when dry to the touch and keep the plant in cooler temperatures if possible. Late spring through summer, water regularly and apply a fertilizer periodically at half strength. Schlumbergera likes to be slightly root-bound – so only repot every 2-3 years into a slightly larger pot. Come fall, fertilize with a high phosphorus fertilizer, continue watering, and keep your eye on the calendar so that you can begin the forcing process again when the time is right.