Holiday Cacti

By Sam Burbach, Education & Programming Coordinator – 11/24/2020

While outdoor flowers have faded in our region and we take a break from gardening outdoors for a while, the time of indoor plants is upon us, especially holiday plants. In celebration of Thanksgiving this week, we’re going to talk about holiday cacti. Cacti are loved as indoor plants since they do well with relatively low care, have beautiful, vibrant flowers, and can be rather long-lived.

You can find Christmas Cactus plants at many stores this time of year. As the colors outside are fading, and we’ll soon see white once the snow starts falling, the bright blooms on this cactus, which flowers in winter, are sure to bring a smile to your face and hopefully make you think warm thoughts!

You might be thinking, “wait, I thought you said in celebration of Thanksgiving?!” Well, did you know…? There is a Thanksgiving Cactus and a Christmas Cactus! (There is even an Easter Cactus, but we’ll just briefly discuss that at the end.) These are distinct species of cacti with slightly different characteristics, although many times you will see Thanksgiving Cacti labeled as Christmas Cacti.

Let’s first discuss how to tell a Thanksgiving Cactus from a Christmas Cactus.

Thanksgiving Cactus (Schlumbergera truncata)

The Thanksgiving Cactus gets its common name from its typical time of flowering in late fall, around Thanksgiving. Thanksgiving Cacti are often labeled and sold as a Christmas Cactus, but the easiest way to tell if you have a Thanksgiving Cactus or Christmas Cactus is by looking at the flattened stem segments, which are botanically called phylloclades. Each phylloclade on a Thanksgiving Cactus will have 2-4 pointed serrations along the margin. A second distinguishing feature is to look at the pollen-bearing anthers on the flowers; on a Thanksgiving Cactus the anthers are yellow.

Christmas Cactus (Schlumbergera x buckleyi)

A Christmas Cactus is a hybrid created from a Thanksgiving Cactus (Schlumbergera truncata) and Schlumbergera russelliana, which contributes to their very similar appearance. Again, you can look at the phylloclades to tell the two apart. A true Christmas Cactus will have scalloped serrations on the margin of each phylloclade. And if we look at the flowers, a Christmas Cactus will have pink to purple-brown anthers. A true Christmas Cactus often flowers about a month later than a Thanksgiving Cactus, thus putting its flowering time in December closer to Christmas.

How to care for a holiday cactus

Holiday cacti can be very long-lived, and a single plant may be passed down from generation to generation. It helps that they are relatively easy to care for, however they’re not quite like the cacti we think of growing in a hot, dry desert and they do require some special treatment to ensure a nice bloom from year to year.

Holiday cacti are epiphytic plants native to the rain forests of Brazil. Epiphytes are plants that grow on another plant but are not parasitic towards that host plant. Orchids, air plants and Spanish moss are common examples of epiphytes. Holiday cacti grow on the branches of trees in the rain forest with their roots anchoring them in place high up off the ground. These native growing conditions include indirect sunlight, daytime temperatures around 75-80 degrees (rather than desert cacti in 95-100+ degree temperatures), cooler nighttime temperatures, especially in winter, and frequent rain where the water runs off quickly since the roots are anchored to tree branches rather than sitting in soil.

To care for your holiday cactus at home, set it in a location with bright but indirect light. It is also important to place it in a location away from extreme temperature fluctuations, such as near a heat vent or drafty window. Water your cacti when the soil becomes dry during spring and summer and keep the soil evenly moist during bud formation and flowering, not allowing it to completely dry out. However, do not allow the pot to ever sit in standing water, thus allowing the soil to become over-saturated.

One complaint some people have with holiday cacti is that the plant blooms the year they bought/received it, but then it does not flower again. Holiday cacti produce their flower buds during the fall and, as a houseplant, they require a little extra attention to provide the conditions they need for bud production – primarily cooler temperatures and shorter daylength. The first factor to initiate bud production is cooler temperatures. Nighttime temperatures around 55-60 degrees are ideal for bud formation. The second factor to help with flower bud production, especially if you do not have a location in your home with temperatures in the 50s, is longer periods of darkness. It is best for the plant to receive 14 hours of total darkness, so you may want to move your plant into a dark closet from about 6pm to 8am during the bud formation period to ensure any lights in the home do not disturb the plant. The cactus will need about 4-6 weeks of these conditions to develop flower buds.

Once flower buds are developed, the plant can be moved back to a place in your home receiving its normal filtered light and room temperature. The warmer the room temperature, the sooner the flower buds will likely open. While this is not an exact timeline, you can try to control when your holiday cactus will flower by beginning these techniques approximately 8 weeks before you wish for it to bloom.

Just for fun!

Along with Thanksgiving and Christmas Cacti, there is also an Easter Cactus (Hatiora gaertneri), flowering in, you guessed it, spring! You’ll notice this cactus is a different genus from the other two in the Schlumbergera genus, but it is similar in appearance to the other two holiday cacti and is also an epiphyte native to Brazil. The margins of the phylloclades on an Easter Cactus are very rounded. The flowers are much more star shaped and open during the day and close at night. Easter cacti require much more attention and a longer period for flower bud formation, thus making them much less popular for greenhouse growers to produce.

Resources for additional information about holiday cacti:

• University of Wisconsin-Madison Master Gardener Program: https://wimastergardener.org/article/holiday-cactus/
• Clemson Cooperative Extension: https://hgic.clemson.edu/factsheet/thanksgiving-christmas-cacti/