The Christmas Cactus, or Schlumbergera, is a popular houseplant known for its vibrant, segmented stems and late-year blossoms. Many people acquire these tropical cacti during the holiday season, expecting them to flower only in November or December. Owners are often surprised by a second flush of flowers in the late winter or early spring, sometimes as late as March. This unexpected floral display is a direct response to specific environmental cues that were met again after the initial holiday bloom.
Understanding the Standard Bloom Cycle
The standard bloom time for a Schlumbergera is triggered by two overlapping conditions that mimic its native tropical habitat. The first is photoperiodism, the plant’s response to day length. As a “short-day” plant, it requires long periods of uninterrupted darkness to initiate flower buds.
For successful bud formation, the plant needs approximately 12 to 14 hours of continuous darkness every night for six to eight weeks. Even a brief interruption from a nearby light source can disrupt this process and prevent bud set. This requirement naturally aligns with the shorter days of late autumn and early winter in the Northern Hemisphere, which is why the plant is associated with the holidays.
The second condition is a period of consistently cool temperatures. Flower buds are most reliably set when night temperatures drop, ideally between 50 and 68 degrees Fahrenheit (10 to 20 degrees Celsius). Temperatures between 50 and 59 degrees Fahrenheit can often trigger blooming even if the darkness requirements have not been strictly met. Meeting both the short-day and cool temperature requirements simultaneously allows growers to force the plant to bloom around the holidays.
The Environmental Triggers Causing Late Blooms
A March bloom indicates the plant experienced a second period of the necessary cool and dark conditions in late winter. The initial holiday bloom often exhausts the fall-set buds, and the plant enters a brief rest period. Remaining indoors, the plant can be inadvertently subjected to the same triggers again in January or February.
Secondary Temperature Drop
One common cause is a delayed or secondary temperature drop, often called a “second chill.” If the plant was kept in a warm, brightly lit area during the holidays, it may not have used all its potential to set buds. Moving the plant to a cooler, less-used room, such as a guest room or drafty hallway, can provide the 50 to 60 degrees Fahrenheit night temperatures needed to re-initiate bud setting. This second chill, lasting several weeks, triggers the late bloom.
Inconsistent Light Exposure
Inconsistent light exposure after the holidays also plays a significant role. Plants are often moved away from high-traffic areas after the festive season. This quieter location might inadvertently provide the requisite 13 or more hours of uninterrupted darkness each night, especially in deeper winter months. The reduction of artificial light exposure allows the plant to perceive the longer nights necessary for flowering.
Shift in Watering Habits
A subtle shift in watering habits can also contribute to late flowering. Water is often reduced slightly during the bloom cycle, which encourages the plant to flower. If the plant was kept slightly drier after the holidays and then received a more substantial watering later in the winter, the combination of cool, dark rest followed by moisture signals favorable conditions. The plant responds to this late-winter signal, which mimics the end of the dry season in its natural habitat.
Post-Bloom Care and Forcing Future Flowers
Once the March flowers have faded, the Christmas Cactus enters its vegetative growth phase. The care routine should shift to support healthy stem and root development. First, gently twist off the spent blooms at the joint where they meet the stem segment, a process called deadheading. Pruning can also be done now by twisting off one or two stem segments to encourage a bushier shape and create more potential flowering tips.
During the spring and summer months, the plant requires active growth to store energy for future blooms. Move the plant to a location with bright, indirect light and increase watering frequency, ensuring the top inch or two of soil dries out between waterings. This is also the time to begin a regular fertilization schedule. Use a balanced water-soluble fertilizer, such as a 10-10-10, diluted to half-strength and applied monthly.
To intentionally force the next bloom for the holiday season, restrict water and initiate the cool/dark cycle starting in late September or early October. Reduce watering significantly, only wetting the soil when it becomes quite dry to the touch. Simultaneously, place the plant in a cool location where temperatures will drop to 55 to 60 degrees Fahrenheit at night. Maintaining 14 hours of total darkness each night for six to eight weeks will ensure a robust set of flower buds appear for the winter holidays.