Campbell Vaughn: Tips to take care of a holiday cactus

It is tough to be humble sometimes, especially when you are so good at something that people stop and look in awe.

I wish I could say this about me, but people still stop and look in awe; not at what I have done, but what happens around every Thanksgiving in my office in downtown Augusta. This time every year, anyone that comes by my office gets to gawk at a Thanksgiving cactus that is in full bloom and it is amazing.  

I picked up a small 4-inch holiday cactus from the super friendly folks at Sanderlin Greenhouses when they hosted a meeting for our office a few years back. I took the little guy back to the office and planted it in a nice pot I had in the corner. This cactus just keeps getting bigger and bigger and the reason the plant does so well has nothing to do with my plant growing prowess.

My office faces directly east and literally has an 1880s built curved window the plant sits under and gets indirect light all day long. All I do to keep this plant moving is water it about twice a month and fertilize it three times a year. The rest is done on its own. 

I have always loved these holiday cacti, mostly from a plant my mother had for a gazillion years that was a cutting of my great grandmother’s. It would always bloom for Christmas every year. And I have found they are easy to root and pretty easy to grow.

There are actually two similar plants we know as holiday cacti that bloom in the fall and early winter. They are in the genus Schlumbergera and originate from Brazil. These plants are epiphytes, meaning they live in the branches of trees or on rocks. Other plants that do this are Spanish moss and orchids.  

The two different varieties of cactus that begin to bloom this time of year are the Thanksgiving cactus (Schumbergera truncata) and Christmas cactus (Schlumbergera bridgesii). Supposedly, they bloom for their respective holidays, but growers can manipulate them to bloom earlier or later, so beware.

To distinguish between the two varieties, look at the shape of the flattened stem segments. The Thanksgiving cactus have pointed tooth-like notches and the Christmas cactus have more rounded notches. Another way of telling them apart is that the Thanksgiving cactus has yellow anthers (the male part of the flower that carries the pollen) and the Christmas cactus has purplish-brown anthers. 

How do the plants know when to bloom? It goes back to photoperiod, the amount of daylight compared to darkness. Thanksgiving cacti are short day plants. To set their flower buds, they need 14 or more continuous hours of darkness. It can’t be interrupted with any kind of light. They also need cool night temperatures, between 60-68 degrees. Keeping them outside on a porch is ideal for flower blooms to form in our area.  

Once the cactus blooms, keep the plant above 50 degrees and below 90 degrees or they will drop the buds. Other reasons for bud drop are too much light, cold drafts, over watering, under watering, or a sudden change in temperature.

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After your holiday cactus blooms, cut back on the watering for a few weeks to let it rest. Then water when the soil becomes dry to the touch. Fertilize the plant monthly with an all-purpose houseplant food. A liquid fertilizer like Peters or Miracle Grow works best. Cacti have a high magnesium requirement, so once a month in the summer, water with 1 teaspoon Epsom salt per gallon of water. You’ll actually have more flowers if you stop fertilizing the plant once the summer ends. 

There are a few other things you can do to keep your holiday cactus happy. Make sure your pot has good drainage holes, and keep your cactus somewhat potbound. Repotting is necessary only about once every three years. Additionally, for bushier plants and more flowers, pinch back three or four segments of each stem in June. You can also use these prunings to propagate a new plant. Just place the cuttings about an inch deep in potting mix (you want one of the joints between the segments to be underground) and water the soil well. You can also cover the container with a clear plastic bag secured with a rubber band around the container to create a mini-greenhouse for about five weeks, until you have roots. The only major disease these cacti have is root rot, which can be prevented by avoiding excessive watering. 

My final advice is to put keep your cactus outside on a porch for most of the year, after the danger of frost in the spring until November. If you don’t have a porch, put the plant under a tree where it can get filtered sunlight. The holiday cacti will reward you with blooms galore for your holiday festivities.