Poinsettia: The Christmas Flower That Blooms in the Dark

Poinsettia plants (Euphorbia pulcherrima) are popular Christmas decorations and are also the highest selling potted plant in the world

The poinsettia plant (Euphorbia pulcherrima) is the equivalent of Mariah Carey’s All I Want for Christmas Is You. You don’t even remember they exist until the first day you walk into a store in November and suddenly it’s the holiday season and Christmas is coming.

And then you’re positively bombarded with them until January 1 at which point Mariah Carey probably gets her giant royalty check for the year (a 2016 study by The Economist found that Carey makes about $2.5m per year for the song and the song had made $60m until that year) and goes on vacation and all the poinsettias just…disappear.

And just like Mariah’s popular Christmas bop, poinsettias are economically important—they’re the highest-selling potted plant in the world. During the holiday season, the six weeks leading up to Christmas, $250 million worth of poinsettia plants—70 million plants—are sold in the United States alone. The plants are even more popular in Europe. There are over 100 different varieties of poinsettia plants patented in the United States.

Poinsettia © Rex Vogel, all rights reserved

History of the Poinsettia

Poinsettias were cultivated by the Aztecs and though they didn’t grow in the capital city of Tenochtitlan—now Mexico City—Aztec royalty imported the flowers from lower elevations during the winter months for use as a medicine to control fevers and as a reddish-purple fabric dye.

The Nahua people of Mexico and Central America call these Aztec favorites cuetlaxochitl but they go by many other names, too—lobster flower, flame leaf flower, La Flor de la Nochebuena (Christmas Eve flower).

But poinsettia is probably the weirdest name of all because it’s just a shout-out to the American diplomat who is credited with being the first to bring them back to the U.S. from Mexico in the 19th century. Joel Roberts Poinsett was the first U.S. minister to Mexico and as an amateur botanist is said to have sent some cuttings back to his home in South Carolina from Southern Mexico in 1828 although there is no irrefutable proof of this.

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Poinsettia © Rex Vogel, all rights reserved

What is known is that the plant was on display in Philadelphia in 1829, associated with Poinsett’s name. The plant was immediately popular and was known henceforth as the poinsettia although it didn’t receive its official Latin name until 1934 when German botanist Karl Willde was given a cutting by a Scottish friend who had seen it in Philadelphia and named it Euphorbia pulcherrima.

In the 1920s the Ecke family of Encinitas, California started farming poinsettias and they tirelessly pushed them as a symbol of the Christmas season. Today, around 70 percent of the poinsettia plants you buy in the United States come from Ecke Ranch and poinsettia care is their lifeblood.

Poinsettia © Rex Vogel, all rights reserved

Caring for Poinsettias

The length of time your poinsettia will give you pleasure in your home is dependent on the maturity of the plant when you buy it, and how you treat the plant. With care, poinsettias should retain their beauty for weeks and some varieties will stay attractive for months.

After you have made your poinsettia selection, make sure it is wrapped properly because exposure to low temperatures even for a few minutes can damage the bracts and leaves.

Unwrap your poinsettia carefully and place it in an indirect light. Six hours of light daily is ideal. Keep the plant from touching cold windows.

Keep poinsettias away from warm or cold drafts from radiators, air registers, open doors, and windows.

Poinsettia © Rex Vogel, all rights reserved

Ideally, poinsettias require daytime temperatures of 60 to 70 degrees Fahrenheit and nighttime temperatures of around 55 degrees. High temperatures will shorten the plant’s life. Move the plant to a cooler room at night, if possible.

Check the soil daily. Be sure to punch holes in foil so water can drain into a saucer. Water when soil is dry. Allow water to drain into the saucer and discard excess water. Wilted plants will tend to drop bracts sooner.

Fertilize the poinsettia if you keep it past the holiday season. Apply a houseplant fertilizer once a month. Do not fertilize when it is in bloom.

With good care, a poinsettia will last 6-8 weeks in your home or RV.

Poinsettia © Rex Vogel, all rights reserved

How to keep a Poinsettia alive

Every houseplant—even a hyper-seasonal one—is kept alive somewhere year-round. Poinsettias hail from the mid-elevation regions of Mexico and Central America where they can grow over 10 feet tall as a perennial winter-flowering shrub with milky sap and branches so long they sometimes look like vines.

The big, showy red, white, or pink flowers we’re used to seeing aren’t actually the poinsettia’s flowers at all, but modified leaves called bracts. The flower buds are the small yellow buds in the middle of the colorful bracts.

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Poinsettia © Rex Vogel, all rights reserved

When you buy a poinsettia at the grocery store it comes already sporting its brightly colored, fancy bracts. You have no idea how hard it was to get them there. Fritz Bahr, the author of Fritz Bahr’s commercial floriculture: a practical manual for the retail grower (1937), described the delicate and finicky poinsettia thusly: “Perhaps no other plant or flower we handle during Christmas week is more short lived, wilts quicker, or is more disappointing to those who receive it; yet, when the next Christmas comes around, there comes again the same demand for poinsettias and the disappointments of a year ago are all forgotten.”

Over time, floriculturists overcame some of these problems but until the mid-1950s, growing poinsettias and getting them into the hands of Christmas revelers in relatively good shape was a real trick. That was, until somebody realized poinsettias need just one thing to turn their green bracts red, pink, or white: total darkness.

In order to induce your poinsettia plant to create flower buds and to change the color of its leaves from green in time for Christmas, it must be kept in complete darkness for 16 hours per day. The witholding of light prevents the plant from producing chlorophyll which is what makes plant parts green. This changes the bracts to red, pink, or white, depending on the variety of poinsettia.

So, somewhere around September 21—right around the fall equinox—pull your poinsettia out of its sunny window and move it into 16 hours of uninterrupted darkness (put the plant under a box if necessary to provide total darkness), alternating with 8 hours of bright light every day.

Poinsettia © Rex Vogel, all rights reserved

During the dark period, the plant cannot receive even the slightest bit of light at any time. This applies to your year-old poinsettia as well: If you want your plant to produce flower buds again and to change color, it’s the daily length of complete darkness, not bright daylight that matters most. Discontinue this around Thanksgiving.

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After Thanksgiving, keep your poinsettia in bright light or the full sun of a sunny window, not keeping the potting soil moist or adding excess water but watering it when the well-drained soil is dry to the touch. Poinsettias prefer temperatures around or above 65 degrees Fahrenheit. They will bloom from Christmas until about April—at this point, it’s a good idea to cut your poinsettia down to a 3- to 8-inch stem and let it regrow starting the process over again until the next year.

Poinsettia © Rex Vogel, all rights reserved

Are Poinsettias poisonous to pets and children?

One common urban legend about poinsettias is that they’re toxic to people and animals. One Ohio State University study showed that a 50-pound child would have to eat over 1 pound of poinsettia leaves—between 500 and 600 leaves—for toxicity to become a problem. However, they certainly don’t taste very good and the child who ate them would probably get a terrible tummy ache long before they were poisoned.

The milky sap of the poinsettia is another matter. Most members of the Euphorbia family have toxic sap but the toxin in poinsettias is very mild. However, those with sensitive skin should avoid touching poinsettia sap, just in case.

Worth Pondering…

Flowers are a proud assertion that a ray of beauty outvalues all the utilities in the world.

—Ralph Waldo Emerson