Thanksgiving cactus are a popular winter houseplant because they produce beautiful flowers and are easy to care for though they need more moisture than some might expect for a succulent (image courtesy: planethouseplant.com). 

By John Green, Certified Texas Master Gardener, Orange County Master Gardeners

There are many types of cacti, some of which prefer arid conditions while other varieties, such as the ‘Thanksgiving’ cactus (Schlumbergera truncata) favor environmental conditions with elevated humidity & increased moisture (watering), bright but indirect light, and temperatures ranging between 60 to 68 F. 

Thanksgiving cactus are epiphytes, originating from tropical rainforests of South-Eastern Brazil. These cacti produce astonishing blooms in a range of colors from bright orange, red, and purple to subtle hues of pink and white variations. In the US, there are three cacti varieties which are considered ‘holiday’ cacti: Thanksgiving (Schlumbergera truncata), Christmas (Schlumbergera bridgesii) which are becoming more difficult to find, and Easter (Rhipsalidopsis gaetneri). At first glance, each of these three plant types look remarkably similar. Each type has somewhat similar care requirements, but there are distinct differences between each cacti type as we inspect each type more closely.

The leaves (segments aka truncata) of Thanksgiving cactus are flat and wide, having small, serrated edges. These plants often bloom in shades of pink, yellow, white, or red, which is a remarkably bright contrast to traditional fall décor. The blooms can last from two to four months, but for them to flower again the following year, the cactus requires a dormant stage which is encouraged by providing it with less light and cooler temperatures.

Did You Know: Epiphytes are plants that grow on another plant (known as phorophyte) for structural support but are not parasitic. Many epiphytes are angiosperms (flowering plants) such as Philodendron, Orchids, Monstera, Hoya, Anthurium, and Bromeliads to name but a few. 

Light

Thanksgiving cactus needs bright, indirect light but must be protected from direct sun to prevent sun scalding and burning. Spring and summer months- provide bright, indirect, or filtered light from a north or east-facing window. Never provide afternoon sun which will damage the plant. Transition the cactus to a new location during fall and winter that receives more direct light. 

To encourage blooming in the fall, they require about 4 to 6 weeks of shortened daylight hours, meaning they need between 12-14 hours of complete darkness each night, starting the beginning of September.  

Blooming

Prune plants during the summer months to prepare them for the Thanksgiving blooming period which begins in September. During this time, the plant requires 12 hours of darkness (at minimum) a day. Propagation is simple & easy and starts with a stem that has a few segments (truncata) leaves attached. Allow the stem to callus for a few days (2 to 4) before planting the cutting into pot containing moistened soil. 

Place a tent (plastic bag), securing it with a rubber band to increase the humidity level around the cutting. Remove the tent every three days to allow the cutting to have fresh air for a few hours, then return the tent and in 2 to 4 weeks the cutting will take root. It often takes 2 to 4 years before cuttings will bloom.

Watering

The most important aspect to consider when caring for a Thanksgiving cactus (or any holiday cactus) is watering. The soil needs to remain moist, but cactus will not tolerate being overly saturated or having “wet feet”. These plants grow naturally at the tops of the trees, where there is less ‘retained’ moisture and more filtered sun. Elevated humidity (40 to 60%) encourages this plant, emulating the natural growing environment. I have learned many lessons through trial and error caring for these types of plants.

Ashamedly, I have drowned too many holiday cacti throughout years to count! Learn from my mistakes- my holiday cacti are provided the exact same treatment and care that I provide Hoyas – allow the soil to dry (almost completely between watering) then submerge the pot or hanging basket into water (completely), allowing them to remain submerged for several minutes. Remove and allow container to drain thoroughly, ensuring they do not stand in water. During winter months typically six weeks pass between watering, and during the summer every other week. 

Holiday cacti can be finicky about water quality, so my suggestion is to allow “city” water to diminish chlorine level by capturing a volume of water (5-gallon bucket) and allow it to remain uncovered overnight before watering the plant or providing rainwater instead. 

There are distinct differences between the three ‘holiday’ cacti varieties. Thanksgiving cactus have flattened stems, Christmas cactus flowers are tubular, and Easter cactus flowers are detailed and star-like (image courtesy: gardengate.com).

Feeding 

The growing season is the only time holiday cactus require fertilization. Feeding season is from March through September for Thanksgiving cactus. A proper feeding schedule and with the right fertilizer, blooms should occur in time for Thanksgiving. 

The cactus will begin forming flower buds during the cooler days of fall. Fertilize the cactus using a balanced bloom formula or water-soluble formula for the best results. During midsummer, apply a fertilizer that is high in phosphorus once a month, to enhance the flowers when they bloom. 

Once the cactus stops growing (late in the summer months), it is important to stop feeding the plant. Continued feeding when it is not actively growing leads to salt build up in the flower buds which will hinder them from opening into blooms. Never fertilize a Thanksgiving (or any holiday) cactus when the plant begins to flower, as it can cause the flower buds to drop (speaking from experience). 

A balanced formula fertilizer is best to use when feeding with equal nitrogen, potassium, and phosphorus. A well-balanced fertilizer that can be dissolved in water makes the feeding process simple.  An all-purpose fertilizer such as 10-10-10 or 20-20-20 mix works well by helping to strengthen the roots and the leaves of the plant, in preparation for blooming around the holidays! 

Outside the growing season (feeding season), some gardeners water cactus using a mixture of a gallon of water with a teaspoon of Epsom salt dissolved, to provide magnesium that it needs to grow and bloom properly without stunting its growth. The plant will not need to be fertilized after October because it will go dormant. 

Getting holiday cactus to bloom during Thanksgiving, Christmas or Easter can be tricky, but if you take the time to provide the correct amount of fertilizer, water, and light a reward will be provided to you for the holidays for many years to come!  

Until next week fellow gardeners, let’s go out and grow ourselves a greener, more sustainable world, one plant at a time! Gardening questions answered: jongreene57@gmail.com.

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