Everywhere we turn, we see red. Poinsettias decorate our homes, churches, businesses and stores. How did a tropical plant become such a pervasive symbol of Christmas? Are poinsettias poisonous? And what should I do with my plants once the holidays are over?

With their bright red color (although they also come in salmon and white now), it’s not surprising that we like to brighten a dreary winter landscape with poinsettias. It’s  too bad they’re only available during the holidays; they’ll live for years given the right care.

Poinsettias are members of the Euphorbia, or Spurge, family, as evidenced by their sticky white sap, inconspicuous flowers, and brightly colored bracts. That’s right, those red “petals” aren’t really part of the flower. Look more closely, and you’ll see the true flowers in the center of the bloom. They’re bright yellow. Other Euphorbias follow the same plan, as you can see by this photo of a Cushion Spurge. (Another well-known Euphorbia is the Crown of Thorns.)

In areas where temperatures stay above freezing, poinsettias can become large shrubs or even small trees. I distinctly remember seeing them on a trip to southern Mexico as a child,, where they towered overhead (I was pretty short then). Here in Colorado, and in most of the U.S., they’re strictly indoor plants. Still, they can become much larger than the small cuttings in pots that we buy at Christmas time.

Care & Feeding
Give your potted plant bright light, keeping it near a sunny window. Just don’t let the leaves touch the cold glass if there’s a chance they’ll freeze. Let the soil surface dry, then add water until it runs freely from the holes in the bottom of the container. Don’t let the pot sit in a saucer full of water; soggy soil kills roots. On the other hand, letting the plant wilt leads to premature leaf drop. I check my plants by lifting the pot. If it’s heavy, we’re fine. If it’s light, I know it’s time to water. In Colorado’s low humidity, that may be two (or more) times per week, depending on how big the pot is.

The flowers last longer if the plant is kept on the cool side. Poinsettias thrive at 65° to 70°F during the day. Nights can be cooler, although it’s best to keep the plant above 60°, as root rot is more common in colder temperatures.

Once the bracts fade and drop, experts at Ohio State University recommend giving the plant a rest period. Starting around April 1, allow your poinsettia to go dormant. Store the plant, barely damp, in a cool (60°) room, mimicking “winter” in the tropics. Be sure you don’t let the stems shrivel—that would be too dry, and fatal to your plant!

About the middle of May, bring your plant in from the “cold,” cut the stems back to about four inches, repot it in coarse potting mix, and water it well. Then put it back in that bright window. Once new growth appears, feed every two weeks with any houseplant fertilizer, mixing it according to the directions on the package. You can leave your plant indoors all summer, or set it outside once the weather warms. Just remember that frost kills.

Getting your poinsettia to rebloom is a bit complicated. Keep plants bushy by pinching out the terminal buds on the branches, but stop by September 1. Then allow buds to set. This occurs when days become shorter than nights, as happens after the fall equinox (usually September 21). Make sure the plants aren’t exposed to artificial light during this time. Flowers appear approximately ten weeks later—just in time for the holidays.

The Christmas Connection
And why do we want poinsettias during the holidays? Wikipedia has one answer:

 The plant’s association with Christmas began in 16th century Mexico, where legend tells of a young girl who was too poor to provide a gift for the celebration of Jesus’ birthday. The … child was inspired by an angel to gather weeds from the roadside and place them in front of the church altar. Crimson “blossoms” sprouted from the weeds and became beautiful poinsettias. From the 17th century, Franciscan friars in Mexico included the plants in their Christmas celebrations. The star-shaped leaf pattern is said to symbolize the Star of Bethlehem, and the red color represents the blood sacrifice through the crucifixion of Jesus.

They’re Yucky
Finally, are poinsettias poisonous? Many Euphorbias are pretty dangerous in that regard, but happily, poinsettias won’t kill you. According to the University of Illinois Extension,

A study at Ohio State University showed that a 50-pound child would have to eat more than a pound-and-a-quarter of Poinsettia leaves (500 to 600 leaves) to have any side effects. The most common side effects that have been reported from Poinsettia ingestions are upset stomach and vomiting. The leaves are reportedly not very tasty, so it’s highly unlikely that kids or even pets would be able to eat that many!

An article at Snopes.com confirms this, and stresses that the plant tastes downright awful. So feel free to fill your home with these safe and showy plants. Then keep them growing all year long.