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University
of Rhode Island GreenShare Factsheets
Holiday
Cacti
The
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. Red
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. Begin
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. Holiday
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. Holiday
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. The
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. Holiday
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 cactus. By
Cheryl Cadwell, URI Master Gardener
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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