Reblooming Christmas and Thanksgiving Cacti Christmas Cactus (Schlumbergera
bridgesii) and Thanksgiving Cactus (Schlumbergera truncate) are popular
flowering holiday plants. Both are epiphytes native to the jungles of South
America. Epiphytic plants grow on other plants and use them for support but
not for nutrients. Though these cacti are different species, they will
hybridize and produce varying stem shapes. Christmas cactus normally has
smooth stem segments.
Thanksgiving Cactus has hook-like appendages on each segment.
Flowering will not occur unless induced by temperature and light treatment.
If the temperature is held at 50 to 55 degrees F, flowering will occur
regardless of day length. But flowering usually is not uniform. Temperatures
below 50 degrees F prevent flowering. Nights greater than 12 hours long and
temperatures between 59 and 69 degrees also can generate flowers.
Twenty-five consecutive long nights is enough for flower initiation. Nights
will naturally become greater than 12 hours close to the fall equinox, which
is on September 23 this year. A plant receiving natural sunlight but no
artificial light during night hours, will have this 25-day requirement met
about October 20. It takes an additional nine to 10 weeks for flowers to
complete development and bloom.
Both of these cacti like bright indirect light. Too much sun may cause
leaves to turn yellow. Common household temperatures are fine. Keep soil
constantly moist but not waterlogged. These plants seem to flower best if
kept a little pot bound. If you need to repot, try waiting until spring.
By: Ward Upham