Help your holiday cacti provide outstanding blooms


Their blooms are magnificent, they can be long-lived and sometimes passed down to descendants and are easy to care for once you understand their needs. The Thanksgiving cactus (schlumbergera truncata) and Christmas cactus (schlumbergera bridgesii) are popular fall and winter blooming houseplants native to Brazil and are available in a wide variety of colors including red, rose, purple, lavender, peach, orange, cream and white.

Unlike the cacti of the desert southwest, these plant species grow as epiphytes among tree branches in shady rain forests, and their pendulous stems make them a great choice for hanging baskets.

Christmas cacti have flattened leaves with rounded teeth on the margins as opposed to the Thanksgiving cactus that has pointed teeth.

Under normal conditions, the holiday cacti will bloom close to the holiday suggested in its name. Florists will often force plants into bloom at other times.

To make things really confusing, most of the Christmas cactus sold are actually Thanksgiving cactus and will bloom in subsequent years at Thanksgiving time. So, don’t be surprised if the plant you bought last year at Christmastime is blooming now.

A second method to distinguish between these two cactus species is based on the color of the pollen-bearing anthers. The anthers of the Thanksgiving cactus are yellow, whereas the anthers on the Christmas cactus are purplish-brown.

The holiday cacti grow best in light shade. Full sunlight is beneficial during fall and winter, but bright sun during the summer months can make plants look pale and yellow. Ideal spring and summer growth occurs at temperatures between 70 to 80 degrees F during its growing season, from April to September.

During the fall, the Thanksgiving and Christmas cacti depend upon shorter day lengths (8 to 10 hours) and cooler temperatures to set their flower buds. Do not let temperatures rise above 90 degrees once the flower buds are set in the fall. Continuous warm temperatures can cause flower buds to drop. Do not leave these cacti outside if temperatures will drop below 50 degrees.

The secret of good flower bud production during the fall involves temperature regulation and photoperiod (length of day and night) control. To initiate flower buds, the plants need:

• Bright light.

• Long nights. Fourteen hours or more of continuous darkness each day is required before flower bud set will occur. Long nights should be started about the middle of September and continue for at least six continuous weeks for complete bud set. Note that as little as two hours of interrupted lighting will inhibit flower bud set. Buds normally will be visible in three to four weeks. The photoperiod has no effect on flowering once the buds are set.

• Fall growing temperatures should be kept between 60 and 68 degrees, but as close to 68 degrees as possible for maximum flower production. Plants grown with night temperatures between 50 and 59 degrees will set flower buds regardless of day length, but growth will be slower and bud drop may occur at 50 degrees.

• Pinching back the stems in early June to promote branching and more terminals for more flowers.

• Pinching at the end of September to remove any terminal phylloclades that are less than four-tenths of an inch long and to make all stems approximately the same length.

These short and immature stem segments will not initiate flower buds until mature. After a short phylloclade is removed, a flower bud forms on the previous, more mature stem segment.

• Water the growing medium when it is dry to the touch. The holiday cacti are tolerant of dry, slightly under-watered conditions during the spring and summer. Do not let the soil become waterlogged, especially during the dark days of winter, but do not let the soil completely dry out, either. However, following bud set in the fall, the growing medium must be kept evenly moist to prevent flower bud abscission. Never let water stand in the saucer beneath the pot.

• Fertilize plants monthly from the time new growth starts in late winter or early spring and throughout the summer using a one-half strength soluble fertilizer, such as a 20-10-20 or 20-20-20 with trace elements. Holiday cacti have a higher requirement for magnesium than many plants. Fertilize monthly during the growing season with Epsom salts mixed at 1 teaspoon per gallon of water, but do not apply the same week as the regular fertilizer. Stop fertilization during the late summer for greater flower bud production in the fall.

• The holiday cacti flower best when kept somewhat pot-bound. Repotting is necessary only about once every three years and is best done in the spring.

The potting medium must be well-drained with good aeration, as these epiphytic cacti do not grow well in heavy, wet potting mixes. A good mix may contain 60-80 percent potting soil with 40-20 percent perlite. Choose a good brand of potting soil which is pH balanced.

• Holiday cacti are easy to propagate by cuttings taken in May or June. Pinch off sections of stems with three to five stem segments on each. Allow the cut ends of the sections to callus by placing them outdoors in the shade for a day or two.

Choose a well-drained potting soil and new or disinfested containers for rooting. Place three cuttings at approximately 1 inch deep into the potting soil of a 4-inch container, or use five cuttings in a 6-inch container.

Water the soil well and cover the plants and rooting container with a clear plastic bag secured with a rubber band around the container. The plastic bag will act as a miniature greenhouse to keep the relative humidity at 100 percent to enhance rooting. Place the container in bright, indirect light until roots have formed — three to eight weeks. At this time the plastic bag can be removed and a diluted fertilizer solution can be used at watering.


The Thanksgiving and Christmas cacti commonly drop unopened flower buds, which may be induced by an excessive number of buds or a sudden change in temperature, light or other environmental factors, such as drying out of the growing medium.

Lack of flowering is often due to light interrupting the long night period (14 hours) that is required for flowering initiation to occur. Street lights, car lights or indoor lighting can disrupt the required dark period.

The above information was taken from articles written by Sandra Mason, extension educator with the University of Illinois and Joey Williamson and Nancy Doubrava, horticulture specialists with Clemson University.

Free wood chips

The wood chips that helped keep things dry during the fair are available to anyone for pickup. If you are interested, just haul it away. There is no need to call the Extension office for permission.

CPR and first aid 

CPR and first aid certification classes are now being offered monthly by the CSU Extension office on the second Monday and Wednesday of each month from 6 to 10 p.m.

We will also schedule classes on additional dates with five or more registrations.

Cost for the classes is $80 for combined CPR/first aid and $55 for individual CPR or first aid. The type of first aid information provided will vary by the needs of the audience. Group rates are available.

For more information or to register, call the Extension office at 264-5931.