Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
November, 2008
Regional Report

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This Thanksgiving cactus is blooming right on time.

Holiday Cactus

I used to think that my "Christmas" cactus, which blooms at Thanksgiving every year, was just impatient. That is, until I learned that there are two distinct, yet related, species.

Both Thankgiving cactus (Schlumbergera truncata) and Christmas cactus (S. russelliana) respond to the shortening days of autumn by setting buds in preparation for a holiday show of flowers. Thanksgiving cactus just responds about a month sooner. To tell them apart, examine the leaf pads: S. truncata has fleshy spikes on the sides of the stem segments, while on S. russelliana the segments are gently lobed. Get one of each and enjoy flowers during both holiday seasons!

What Makes a Cactus a Cactus?
Although these plants are true cacti, they do not hail from the desert, but rather are native to the Brazilian rainforest. So what, exactly, makes a cactus a cactus? As is often the case in plant classifications, it's all about the flowers. According to an article by Mark Dimmitt, Director of Natural History at the Arizona-Sonora Desert Museum:

"Most people think they know a cactus when they see one, but they are often mistaken. All cacti are succulents, but not all succulents are cacti. Agaves... and aloes are among the swollen or spiny plants often mistaken for cacti. However, the term cactus refers to a particular family of plants defined by a distinctive flower pattern. To be a cactus, the plant must produce flowers with the following characteristics: many tepals (combined sepals and petals) that intergrade with each other; many stamens (usually hundreds), and numerous stigma lobes (rarely only three). If a plant lacks such a flower, it cannot be a cactus."

Caring for a Holiday Cactus
As is usually the case, the native habitat of a holiday cactus gives clues to its care. Schlumbergera are found high in the canopy of rainforest trees, where they root in plant debris caught in the tree branches. Provide the plants with rich, organic soil. Similarly, because in their native habitat the plants are shaded by the high canopy, give your holiday cactus bright light but little direct sun. Keep soil slightly moist, neither saturated nor bone dry.

Encouraging Blooms
My cactus blooms on schedule with no prompting from me, but there are steps you can take to help the process. I usually keep the plant outdoors on the porch until temperatures drop into the 40s at night because cool nights help stimulate the formation of flower buds. If your plant lives indoors year-round, you may need to treat it more like a poinsettia and provide it with total darkness every night for at least three weeks in September to early October to encourage bud set.

Holiday cacti are ridiculously easy to propagate: In spring or summer, break off a section of stem containing 2 to 4 segments, let it sit for a day or so, then stick the cut end about a half inch into a pot of moist sand, vermiculite, or potting soil. Roots should form in about a month.

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Today's site banner is by nmumpton and is called "Gymnocalycium andreae"