Terry Brite Delvalle| Florida Times-Union
Poinsettias might be the number one plant at Christmas time, but most people toss them once the holidays are over. That is not the case with the Christmas cactus because it makes a very good houseplant. This plant is a keeper, and with proper care it will keep on giving during the holiday season for years to come.
During most of the year Christmas cacti may go unnoticed but they are spectacular when in bloom. Stems develop a graceful weeping appearance when weighed down with flowers, which range in color from blood red to pink, orange, yellow, white and bi-colors.
Christmas cacti are native to southeast Brazil and are epiphytes that grow on trees in shady, humid forested areas. They are part of a small genus of cacti that include six different species. The species sold at Christmas time include the Thanksgiving cactus (Schlumbergera truncata) and Christmas cactus (Schlumbergera bridgesii). Although the two species are similar, there are minor differences. One way to tell the difference is by looking at the margins of the flattened stem segments, called phylloclades. On Thanksgiving cactus, the phylloclade margins have two to four saw-like projections while on Christmas cactus they are more rounded. Another distinction is that the pollen bearing anthers of Christmas cactus are pinkish-brown whereas anthers of the Thanksgiving cactus are yellow. All will bloom at the appropriate time based on their names if grown under natural lighting conditions. However, by manipulating growing conditions, both species can be forced to bloom at Christmas, and are then referred to as “Holiday Cacti.” This might surprise you but most holiday cacti purchased at Christmas time are actually Thanksgiving cacti because they are easier for growers to force.
FORCING
Timing is everything with Christmas cacti. Like poinsettias and chrysanthemums, they are considered short day plants. When the days are long in the summer they produce new growth. They then form flower buds in response to shorter day-lengths in the fall. Cooler temperatures associated with fall also help stimulate flower production. As fall approaches, plants benefit from a 10-degree drop in temperature. If plants are outdoors, bring them inside if temperatures rise above 90 degrees during budset.
If you place your holiday cactus in a location that receives natural lighting, plants will develop flowers without any additional effort because of the shorter day lengths. If you don’t have a spare room that can be kept dark at night, plants can be covered with a cardboard box or moved to a closet from 5 p.m. to 8 a.m. each day for six weeks starting around mid-September. Just remember to uncover or bring them out of the closet each day and place them back in a sunny area. Plants should bloom 10 weeks after short days are initiated. Once buds begin to form, plants can be placed in areas exposed to artificial lighting at night without negative effects.
GROWING TIPS
If you are the new owner of a holiday cactus, find a spot indoors that receives bright light but not hot afternoon sun. An area near an eastern-facing window is usually good, and plants can also be grown outside in shady areas during warmer months. Ideal temperatures during the growing season are from 70 to 80 degrees, which is in the range of most households. If growing them outside, remember to bring them inside if temperatures drop below 50 degrees.
Watering is one of the keys to success with these plants. When in bloom, keep the soil slightly moist but not soggy. Don’t allow the soil to dry out, or the buds/flowers may drop. Once the bloom cycle is over, keep the plant a little drier. Check the upper inch or two of the soil and add water when it dries out. Never let plants sit in a saucer of water or they will be plagued with disease problems.
Fertilize monthly with a liquid houseplant fertilizer at half strength starting in late winter, and continue through the summer. On one of the off weeks each month, fertilize with 1 teaspoon of Epsom salts per gallon of water to prevent magnesium deficiency. Stop fertilizing the plants in late summer to allow them to prepare for flower production.
To create more flowers, lightly prune the stems in early June to create more branching when plants are actively growing.
Plants will flower better if they are pot-bound, but it is usually a good idea to replace the soil every two to three years. Select a media that is well-drained and light. If the soil holds too much water, the plant stems and/or roots will rot. A suitable mix is one with three parts of a good quality houseplant potting mix and two parts perlite.
PROPAGATION
These plants are easily propagated in May or June by starting with stem cuttings of three to five sections. Allow the cuttings to callous over for a few days; then insert cuttings one inch deep in a media with good drainage. Place multiple cuttings in the container so plants will become full once they establish. Cover with a plastic bag; a gallon-size bag creates the perfect greenhouse over a one-gallon pot. Place the container in bright indirect light, and cuttings should be rooted in about one to two months. Test for success by gently pulling on the cutting. If it doesn’t come out of the soil easily, roots have formed. Once rooted, remove the plastic bag and begin the process of watering with a light fertilizer solution. With any luck, you will have plants in bloom that you can share with friends and family for the holidays in 2018.
Terry Brite DelValle is a horticulture extension agent with the Duval County Extension Service and the University of Florida/IFAS.