The Christmas Cactus, botanically known as Schlumbergera, is a popular houseplant celebrated for its vibrant winter blooms. Unlike desert cacti, this plant is an epiphyte, meaning it naturally grows on trees in the humid, mountainous rainforests of Brazil. The tubular flowers that emerge from the segmented stems bring a splash of color to indoor spaces during the holiday season. The extensive range of flower colors available today is a result of decades of dedicated hybridization.
The Core Color Palette
The color spectrum for Christmas Cactus flowers is broad, extending beyond the original magenta and pink tones of the wild species. This diversity is due to the creation of numerous hybrids by commercial growers. These cultivars allow for a full range of colors, ensuring a shade to match nearly any holiday decor.
True reds and deep magentas represent classic and popular colors, offering a festive, traditional look. Cultivars in this group exhibit intense saturation, often appearing in shades like ruby or scarlet. Moving toward the cooler end of the spectrum, various shades of pink are common, from pale shell pinks to vibrant fuchsia and lavender hues.
The introduction of yellow-flowered varieties, such as ‘Gold Charm’, was an achievement in breeding. These yellows often appear alongside other warm tones, creating apricot, salmon, and orange blossoms. White and cream-colored cultivars offer a contrast to saturated colors, sometimes displaying a subtle pink or yellow blush at the base of the petals. Many modern hybrids are also bicolored, featuring contrasting throats or petal edges.
Distinguishing Holiday Cacti
The term “Christmas Cactus” is often used interchangeably for three related, yet distinct, holiday-blooming plants. The two main types belong to the Schlumbergera genus: the Thanksgiving Cactus (S. truncata) and the true Christmas Cactus (S. x buckleyi). The third is the Easter Cactus, which belongs to a different genus, Rhipsalidopsis.
The simplest way to differentiate the two Schlumbergera types is by examining the edges of their stem segments, which are actually flattened cladodes. The Thanksgiving Cactus has pointed, claw-like projections along the edges, leading to its nickname, “Crab Cactus.” In contrast, the segments of the true Christmas Cactus have smoother, more rounded, or scalloped edges.
Bloom timing also helps distinguish them, though commercial forcing makes this less reliable. The Thanksgiving Cactus typically flowers earlier, starting in late fall, while the true Christmas Cactus blooms closer to Christmas and into January. The Easter Cactus is identified by its rounded stem segments and star-shaped flowers that bloom in spring, usually from March to May. The vibrant color range discussed earlier generally applies to the widely cultivated Thanksgiving Cactus hybrids, which are often sold as “Christmas Cacti.”
Environmental Factors Affecting Bloom Color
The final color of a Christmas Cactus bloom is not solely determined by its genetics; environmental conditions play a role in pigment expression. The intensity of a flower’s color is linked to the concentration of anthocyanin pigments within the petals. These pigments are responsible for the red, pink, and purple shades.
Cooler temperatures during the bud development phase can intensify the expression of these anthocyanin pigments. When a plant is exposed to night temperatures in the range of 50°F to 59°F, the resulting red and purple flowers will often appear deeper and richer. If the same plant is kept in consistently warmer conditions, the colors may emerge as a lighter pink or a muted lavender.
Light intensity also influences the final hue, as bright, indirect light promotes pigment production. Too much direct sunlight, however, can stress the plant and lead to reddish or purplish stress coloration on the stems instead of the flowers. Conversely, very high heat, such as temperatures exceeding 90°F, can cause colors to appear washed out or faded, even in vibrant cultivars. This sensitivity explains why a cactus purchased in deep color may bloom a slightly different shade in a home environment the following year.