A holiday cactus in full bloom is a great holiday gift. This easy-to-care-for
plant generally lives a long life and will easily bloom year after year. In
fact I often hear about holiday cacti being passed down from generation to
generation as a family heirloom.
When selecting a new plant, look for sturdy, healthy green foliage and new
flower buds. Avoid diseased or insect-damaged plants. Before taking them
outdoors, carefully wrap plants to protect them from cold temperatures.
Exposure at freezing temperatures even for a short time can damage leaves and
cause flowers to drop. As with all houseplants, avoid placing plants near
register vents or in drafty areas.
Holiday cacti include the Thanksgiving cactus, Christmas cactus and Easter
cactus. The holiday cacti are easily identified by the stem margins. These
cacti don’t have true leaves; instead they have flattened stem
segments.
The most widely grown species is the Thanksgiving cactus, also called a crab
cactus, Schlumbergera truncata. The stem margins have two to four sawtoothed projections resembling crab
claws. Flowers are produced from late November to late December. Thanksgiving
cacti are often forced into bloom and sold at Christmas time, often misnamed
Christmas cacti. Flower colors include white, red, lavender, salmon, orange and
yellow.
Christmas cactus, Schlumbergera x buckleyi, has scalloped or rounded stem margins. Flowers are generally showy from late
December through March. The flowers are formed at the tip of the segments.
Easter cactus, Rhipsalidopsis gaertneri, have four to six rounded teeth along the stem edges and brownish hairs at the
leaf tips. Shades of pink or red flowers appear from March through May. Easter
cactus may rebloom.
Thanksgiving and Christmas cactus blooms are triggered by day length. They bloom
when they receive 12 to 15 hours of darkness each day for 5 to 6 weeks,
combined with cool night temperatures. Some cacti will bloom if exposed to
prolonged cool temperatures, between 50 and 55 degrees F during the fall,
regardless of day length.
To initiate flower buds, place Thanksgiving and Christmas cacti in a room that
doesn’t receive artificial light at night, such as a spare bedroom or basement. Cacti
can also be placed in an unheated porch until temperatures reach 45 degrees F.
Plants should receive bright light during the day with 55 to 65 degrees F
temperatures.
When plants are in flower, keep them in a bright, indirect light. Ideal
temperatures are 70 degrees F during the day and 65 degrees F in the evening.
Don’t let the soil dry out during flowering. Flower buds will drop from the plant if
it receives too much light, is exposed to drafts or temperature extremes, or if the soil gets too dry.
If plants fail to flower, this could be due to interrupted nights or high
temperatures.
During the growing season when the plant is not in flower, water plants
thoroughly but let the plant dry slightly between waterings. A major disease of
holiday cacti is root rot caused by over-watering. Water when the top inch of
soil is dry to the touch. When the plant is actively growing, between April and
October, fertilize every two to four weeks with a complete houseplant
fertilizer. (Follow the label directions.) Holiday cacti require a bright but
filtered light indoors. Keep in mind that the holiday cacti thrive on neglect.
This winter brighten up the indoors with a flowering Thanksgiving cactus.
This article appears in Dec 11-17, 2008.
