Why Does My Christmas Cactus Bloom Too Early?

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Christmas cactus? No, it’s actually a Thanksgiving cactus. Photo: Peter coxhead, Wikimedia Commons

As I write this in early November, my “Christmas cactus”—I have five of them—are blooming up a storm. But that’s almost two months before Christmas. That can’t be right! But it is, because these plants—and probably the ones you have at home as well—are not really Christmas cactus. Let me explain.

There is indeed a true Christmas cactus, in fact, two of them (Schlumbergera. × buckleyi and its parent S. russelliana), and they do bloom towards the middle or end of December. But they’re not popular with greenhouse growers who prefer the earlier blooming Thanksgiving cactus or crab cactus (S. truncata), which, as the name suggests, naturally blooms in November, shortly before the American Thanksgiving. So when you buy a Christmas cactus, you actually come home with a Thanksgiving one.

How to Tell the Two Apart

The true Christmas cactus has hanging flowers and pendant stems with no pointed teeth. Photo: http://www.plumjam.com

The true Christmas cactus has a distinctly pendent stem, hanging flowers in shades of magenta, and, most obviously, flattened stem segments with smooth, somewhat crenelated edges, but never toothed. And, of course, if your plant naturally blooms at Christmas, that’s another good sign it’s probably the real Christmas cactus.

This plant is generally a pass-along plant, shared between gardeners for generations. It’s rarely sold in nurseries because its long stems shatter too readily, making it difficult to transport. 

Thanksgiving cactus (S. truncata) with its toothed segments and horizontal flowers. Photo: Dwight Sipler, Wikimedia Commons

The Thanksgiving cactus (S. truncata) has stems that grow upright at first, then arch, so it’s more a spreading plant than a distinctly hanging one. Also, its flowers are borne horizontally rather than hanging limply from the stem tip. Most obviously, though, it has distinct teeth on its segments a bit like crab claws, which is why it is also known as crab cactus. Also, unlike the true Christmas cactus, it comes in a wide range of colors: red, fuchsia, magenta, lavender, pink, white, yellow and even orange. 

It’s abundantly found in stores of all sorts in the holiday season, even supermarkets. Under normal circumstances, though, it will bloom well before Christmas, in very late October or in November.

But It Was in Bloom at Christmas When I Bought It …

Just to confuse people, Thanksgiving cacti are usually sold in full bloom at Christmas and you may indeed have purchased yours at that season. But now it blooms in November. Why?

Greenhouse growers have learned that if you grow Thanksgiving cactus cool (which saves on heating for them), they can delay its bloom. And if you can do the same in your home, you can encourage your Thanksgiving cactus to bloom for Christmas. Here’s how:

First, both Thanksgiving cactus and the true Christmas cactus need short days (less than 12 hours of sunlight per day) starting in late September or they won’t bloom at all. So, I suggest you put your plants in a spot that receives no artificial light between 6 p.m. and 5:30 a.m. I put mine in the guest room—we never turn on the lights there at night—but you can simply place your plants behind other plants or a piece of furniture: you just have to make sure no artificial light reaches them at night.

Next, you have to keep your Thanksgiving cactus cool, below 60˚F (15˚C) day and night until just before Christmas. This will slow down the development of its flower buds. Then move the plant into a regularly heated room in mid-December and voilà! Flowers for Christmas!

Or Enjoy the Bloom Whenever It Occurs

Personally, I’ve learned to love flowers whenever they appear. So, I don’t struggle to force my Thanksgiving cactus to bloom for Christmas. If they want to bloom their heads off in November, that’s fine with me. Besides, I do have a real Christmas cactus that will cover the holiday season: it’s always covered in bloom on Christmas Eve. Nor am I upset when both my Christmas cactus and Thanksgiving cactus rebloom in late February or March, which most of them do. Hey, sometimes one will bloom yet again in midsummer, when the days are long (I have no explanation as to why that happens!) and that’s fine with me too.

I say just enjoy the bloom, whenever it occurs. But then, I am a laidback gardener!

Adapted from an article originally published on November 15, 2015.

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When Your Christmas Cactus Blooms Too Early

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The toothed stems and horizontal blooms say this is not a Christmas cactus, but a Thanksgiving cactus.

Your Christmas cactus is already in bloom well before Christmas? That’s normal… because it’s not a Christmas cactus. Let me explain.

There is indeed a true Christmas cactus, in fact two of them (Schlumbergera russelliana and a nearly identical hybrid S. x buckleyi), and they do bloom towards the middle or end of December. But they’re not popular with greenhouse growers who prefer the earlier blooming Thanksgiving cactus or crab cactus (S. truncata), which, as the name suggests, naturally blooms in November, shortly before the American Thanksgiving.

How to Tell Them Apart

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The true Christmas cactus has pendant flowers and pendant stems with no pointed teeth.

The true Christmas cactus has a distinctly pendent stem, hanging flowers in shades of magenta, and, most obviously, flattened stem segments with smooth, somewhat crenellated edges, never toothed. It is rarely sold in nurseries because its long stems shatter too readily, making it difficult to ship. And, of course, if your plant naturally blooms at Christmas, that’s another good sign it’s probably the true Christmas cactus.

20151115AENThe Thanksgiving cactus has stems that grow upright at first, then arch… and its flowers are borne horizontally rather than hanging limply from the stem tip. Most obviously, though, it has distinct teeth on its segments a bit like crab claws, which is why it is also known as crab cactus. Also, unlike the true Christmas cactus, it comes in a wide range of colors: red, fuchsia, magenta, lavender, pink, white, yellow and even orange. It abundantly found in stores of all sorts in the holiday season, even supermarkets. Under normal circumstances, it will bloom in very late October or in November.

But My Cactus Used to Bloom at Christmas…

Just to confuse people, Thanksgiving cacti are often sold in full bloom at Christmas and you may indeed have purchased yours at that season. But now it blooms in November. Why?

Greenhouse growers have learned that if you grow Thanksgiving cactus cool (which saves on heating for them), they can delay its bloom. And if you can do the same, you can encourage your Thanksgiving cactus to bloom for Christmas. Here’s how:

First, both Thanksgiving cactus and the true Christmas cactus need short days (less than 12 hours of sunlight per day) starting in late September or they won’t bloom at all. So I suggest you put your plants in a spot that receives no artificial light between 6 pm and 5:30 am. I put mine in the guest room – we never turn on the lights there at night – but you can simply place your plants behind other plants or a piece of furniture: you just have to make sure no artificial light reaches them at night.

Next, you have to keep your Thanksgiving cactus cool, below 60˚F (15˚C) day and night until just before Christmas. This will slow down the development of its flower buds. Then move the plant into a regularly heated room in mid-December and voilà! Flowers for Christmas!

Enjoy the Bloom Whenever It Occurs

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Thanksgiving cactus in full bloom.

Personally, I’ve learned to love flowers whenever they appear. So I don’t struggle to force my Thanksgiving cactus to bloom for Christmas. If they want to bloom their heads off in November, that’s fine with me. Nor am I upset when both my Christmas cactus and Thanksgiving cactus rebloom in late February or March. Hey, sometimes one will bloom yet again in mid-summer, when the days are long (I have no explanation as to how that happens!) and that’s fine with me too.

I say just enjoy the bloom, whenever it occurs. But then, I am a laidback gardener!

Laidback Gardener Tip of the Day

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Thanksgiving Cactus or Christmas Cactus?

Your Christmas cactus is already in bloom, well before Christmas? That’s probably because you don’t have a true Christmas cactus (Schlumbergera russeliana and its hybrid, S. x buckleyi), but rather a “Thanksgiving cactus” (S. truncata ), so-called because it naturally blooms in November. Greenhouse growers produce Thanksgiving cactus by the millions in barely heated greenhouses designed to delay their bloom until Christmas. So when you buy them the first year, they bloom right on time. But the next year and the following years, no such luck: they bloom heavily, but in November.

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Christmas cactus (Schlumbergera russeliana)

The true Christmas cactus (S. russeliana and S. x buckleyi) can be recognized by its hanging stems with rounded teeth and fuchsia flowers that hang downwards. Commercial growers don’t appreciate its weeping stems because they mingle with those of its neighbors, making the plant hard to ship… and it is also more costly to produce, as it needs a heated greenhouse. It is often found in private homes, as it is a long-lived houseplant, but almost never in garden centers.

novembre 27.3There are many varieties of Thanksgiving cactus (S. truncata) on the market ranging in color from pink to purple, red, white and yellow. They have stems that are generally upright in their youth, although they arch as they grow, and have distinctly pointed teeth, like crab claws. The flowers are carried slightly upright or horizontally. They are readily found in garden centers during the holiday season and also in supermarkets, box stores, and florist shops.

To delay flowering of your Thanksgiving cactus until Christmas next year, keep it cool, 60˚C (15˚C) or less, throughout the autumn. This is what the greenhouse growers who produce them do: by growing them in barely heated greenhouses, they manage to produce Thanksgiving cactus cheaply, just in time for Christmas.