The Christmas cactus (Schlumbergera bridgesii) earned its common name with the timing of its bloom, which occurs at Christmas if the plant has been given 8 weeks of long nights -- 13 hours or more of dark - for eight weeks preceding Christmas. As a tropical species, it performs best indoors but also thrives in sheltered areas outdoors in U.S. Department of Agriculture plant hardiness zones 10 to 12. An established Christmas cactus typically suffers few problems, although some may develop red-tinged foliage as a result of poor growing conditions, infections or inadequate care.
Cultural stress is one common reason that Christmas cactus develops red foliage, specifically if the plant is exposed to direct sun in summer or doesn't receive enough water. As a tropical forest species, this cactus performs best in partial shade during warm seasons; however it prefers full sunlight during midwinter. It requires slightly more water than many other cactus species and should be irrigated whenever their soil feels dry 1 inch below the surface. If an established Christmas cactus develops reddish foliage but otherwise appears healthy, evaluate its light exposure and move if necessary. Likewise, adjust the moisture level in the soil and don't allow it to dry out for too long between watering.
Overwatering causes damage to roots both by limiting their oxygen exposure and by weakening their tissue. Root rot is a common result of overwatering. It is characterized in Christmas cactus by mushy tissue, wilting and pink or reddish discolorations on the leaves. Another tell-tale sign of root rot is a musty or sour smell in the soil. An affected plant should be repotted into fresh, unused medium and left unwatered for two to three weeks. Prune off the badly damaged foliage, and slowly return the plant to a normal water schedule by letting the soil dry out in the top 1 inch between waterings. Disinfect pruning blades before and after use by wiping with rubbing alcohol.
Christmas cacti may develop an infestation of cactus cyst (Cactodera cacti) if potted in dirty soil or propagated from an infected plant. As a nematode, cactus cyst primarily affects the roots but can cause a host of symptoms in the foliage. Stunted growth, wilting and reddish discolorations are all common symptoms, but the most unmistakeable sign is seen on the roots in the form of tiny, pearl-like masses. Treatment of cactus cyst is difficult and seldom successful, so prevention is key. Pot the plant in fresh, sterilized medium inside an unused pot and keep it off the ground to limit contact with infested soil. If an infestation occurs, discard the plant to keep the pathogen from spreading.
Red or purple-tinged foliage and wilting are two common symptoms of a magnesium deficiency, which is a common ailment in Christmas cacti. It occurs mainly during the winter months when feeding and watering are restricted and cold temperatures slow the plant's nutrient uptake. The cactus does best in winter at temperatures around 55 to 65 degrees Fahrenheit, according to Missouri Botanical Garden. Correcting a magnesium deficiency can be done with Epsom salts, to the "Green Gazette" newsletter where master gardener Leah Ray says to dissolve 8 heaping tablespoons of Epsom salts in 2 1/2 gallons water, and mix in 1 to 2 drops of dishwashing liquid. Pour the mixture into a spray bottle and spritz the tops and undersides of the foliage. Reapply the mixture every two weeks until the foliage returns to its original color.
- Clemson University Cooperative Extension: Thanksgiving & Christmas Cacti
- Logee's Tropical Plants: Cultural Information-Schlumbergera
- University of Florida IFAS Extension: Holiday Cactus Production Guide
- North Dakota State University Extension: Questions on Christmas Cactus
- Hooper's Garden Center: Care of Christmas Cactus
- University of Arkansas Cooperative Extension Service: Holiday Plants-Holiday (Thanksgiving and Christmas) Cactus
- University of Florida IFAS Collier County Extension:
- Missouri Botanical Garden: Schlumbergera truncata
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