Poinsettias – Oh So Beautiful

It’s that time of the year to celebrate the holiday season again! The lights, the wreaths, and the tree all combine to make one big festive holiday display in and out of our homes. Poinsettias are often part of that display as they are one of the most popular flowers associated with the holidays.   

Native to Mexico, this now-famous holiday plant was first cultivated by the Aztecs and called the Cuetlaxochitl. They were so prized by the Aztec emperor Montezuma that he had them shipped into Mexico City. Today is it is known in Mexico as flor de Nochebuena. Poinsettias became a popular holiday plant because of their colorful bracts (modified leaves). This member of the Euphorbia family can grow 12 to 15 feet tall in the wild! Euphorbia pulcherrima, which translates to “very beautiful,” was given its botanical name by the German botanist Johann Friedrich Klotzsch but was first introduced to the United States by Joel Roberts Poinsett in 1825. Poinsett was the first United States envoy to Mexico and an amateur botanist.He took cuttings of the plant while he lived in Mexico and brought them back with him to South Carolina where he continued to grow them in his greenhouse. As this plant gained popularity and familiarity in the U.S., it was given the name poinsettia after Joel Poinsett. 

Poinsettia varieties have evolved over the years to the point where there are now hundreds of varieties and colors offered to consumers. Years ago, when I started in the industry in retail, we were limited to one red, one white, and one pink variety. Greenhouses had to be covered with black cloth or lit with supplemental lighting in order control the development of the bracts’ color at a staggered rate so that plants were available and fresh throughout the selling season. Breeding has now yielded varieties that will change color earlier in the fall. This is beneficial to retailers who wish to sell poinsettias as early as Thanksgiving. These earlier varieties also mean that growers no longer need to use black cloth to cover entire sections of greenhouses so some plants will develop their color earlier. One of my fondest memories involves my first introduction to a variety called ‘Jingle Bells.’ This poinsettia has red bracts with white and pale pink splotches throughout the red. A guest to our retail store thought that we had splashed bleach on the bracts to make the splotchy marks! Poinsettia colors have multiplied over the years.  Now colors and patterns like lemon yellow, gold, marbled, and splotches are found in retail and garden centers. 

Poinsettias are ‘photoperiodic,’ meaning they need bright light during the day and no light at night for at least 12 hours. It is better to have more hours of darkness to turn the poinsettia leaves into magnificent colors. If the night cycle is interrupted at any time this can delay the coloring of the bracts. When the days start to get shorter after the fall equinox, on or around September 21^st, you will begin to see the process of the leaves turning.  

Many people want to keep their poinsettia plant each year. Poinsettias are tropical so will thrive outdoors during the summer months but must be brought in before the first frost. Labor Day is a good time to bring them indoors. 

To get a poinsettia to turn color and bloom again for the holidays it must start getting long nights and short days. This should begin around September 21^st and last until about mid-November. The plant must be put in complete darkness at the end of each day and brought out during the daylight hours to receive sunlight, water, and fertilizer. I have encountered numerous instances where a poinsettia was put in a dark closet and left there for several weeks only to be revealed that it perished because the plant never emerged from the closet during the day.   

There is widespread belief that poinsettias are poisonous. This is a misconception, though eating the plant is definitely not recommended. Since poinsettias are in the Euphorbia family, they contain a sticky white sap that can cause a skin rash for some. If this is the case, gloves are recommended when working with them. Also avoid contact with the eyes and mouth, and wash tools well after use as the sap make them sticky. 

Poinsettias do not like ‘wet feet.’ A poinsettia will wilt if it is too dry but will also wilt if it is too wet. Constant watering will rot the plant roots. I like to lift up the plant to determine if it needs to be watered. If the pot feels lightweight when lifted, then it probably needs to be watered. Poinsettias are often sold with a decorative foil or outer pot covering; be sure to remove the covering before watering so that the plant does not sit in excess water. Water thoroughly and allow the plant to drain completely before putting the decorative pot cover back on the plant. 

Poinsettias do not need to be fertilized during the holidays but if you plan to keep a plant longer, start fertilizing it when you see new growth in the form of new leaves or stems. An all-purpose household plant fertilizer is fine to use.   

Smithsonian Gardens’ horticulturists grow about 1,800 poinsettias every year. Poinsettia cuttings are ordered in April and arrive sometime between late June and early August.  We grow twelve to fifteen varieties every season. Poinsettia production is extremely labor intensive, but the final product is oh-so rewarding! The beautiful poinsettias are displayed throughout the Smithsonian museums and enjoyed by hundreds of thousands of visitors each year.