popular holiday cactus is a true cactus, even through its appearance
is different from the desert cactus forms. Native to the Brazilian
rain forest, these plants have wide, flattened green stems that
look like leaves (called segments) and produce colorful flowers.
Hybridization has so extended the bloom period of these plants that
the names Thanksgiving, Christmas and Easter Cacti only give an
indication of when they will start to bloom. One way to tell the
difference between the species is to look at their segments. The
"Thanksgiving" cactus (Zygocactus truncatacor) is also called
the "lobster claw" cactus because the leaf segments have points
at the tips of the segments; the "Christmas" cactus (Schlumbergera
bridgesii) segments have smooth edges. The Easter cactus
(Rhipsalidopsis gaertneri) has bristles on the sides of segments
and at the tip of the terminal segments.
is no longer the only color found in holiday cactus. The color range
extends from pure white forms through plants with varying shades
of red and pink. You can also find cactus with peach, salmon, purple
and orange flowers. Gold forms have also appeared recently.
These plants are usually blooming when purchased. Water lightly
and put them in a cool spot with bright light, but not full sun.
If the leaves start looking yellow, the light is too strong. For
best bloom, keep them in a cool location (night temperature of 55
to 60 degrees F). The buds will drop off if the temperature is too
high. Low humidity will also cause bud drop. These cacti may continue
to bloom for months.
to fertilize when blooming stops. Use a dilute fertilizer that is
not too high in nitrogen once a month. A good formulation is 5-10-10
or 10-10-10. When warm weather comes, you can set the plants outside
in a shady location--they can sunburn if exposed to excessive bright
light. Despite the name cactus, they come from the jungles of Brazil
and have the same habitat as orchids and ferns. If they must be
kept indoors, filter the light and keep them in a cool location.
cacti tolerate being pot-bound, but for the health of the plants
they should be repotted every few years. Add new soil and prune
any roots that are brown and lifeless in the spring. The plant can
be returned to the same-sized pot--plants in oversized pots with
rich soil produce a lot of green leaves but very few buds.
Flower buds will begin to set in September or early October. At
this time, stop feeding the plant and reduce watering. If the plants
have been outdoors for the summer, be careful to keep the plant
in a cool location when you bring in the plants in order to avoid
bud drop. The cacti need long nights to set buds. A brief exposure
to light will not stop the budding process, but if there is a porch
or street light outside the window and it shines long into the night,
this may inhibit budding. It is recommended that the plant have
12-14 hours of uninterrupted darkness. Nighttime temperatures need
to be around 50 to 55 degrees F for good bud set and flowering.
cacti can be infested by scales or mealy bugs, but these insects
rarely cause major problems. Wiping the leaves with alcohol can
keep pests in check. Use a systemic insecticide for a serious infestation.
main cultural problem to avoid is overwatering. Wait until the soil
in the pot is quite dry before watering. This is especially important
with the Easter form, which is very sensitive to overwatering.
cacti are very easy to propagate. In spring or summer, cut off a
piece of the plant that has at least two segments. The more segments
on the cutting, the larger plant you will produce--but limit the
piece to 4 or 5 segments, as the small root system will not be able
to provide adequate support and nutrients for too big a piece. Let
the segments dry for a few days so that a callus forms. Then put
the piece into damp sand or vermiculite. In about three to four
weeks roots should have formed. You can then repot it into a small
container filled with a light potting soil. This potting soil should
be composed of about one third sand to avoid overwatering the young
Cheryl Cadwell, URI Master Gardener