Clemson professor shares advice for choosing and keeping poinsettias
CLEMSON — Christmas is the season for decorating with poinsettias, and a Clemson professor who has been studying poinsettias since he was in college in the 1980s has some advice for selecting and caring for this plant.
Faust notes that the colored parts of poinsettias are modified leaves called bracts. At the center of the bracts are the plant’s true flowers, called cyathia.
“When selecting a poinsettia to purchase, consumers should look for a full cluster of cyathia in the center of the showy red bracts,” Faust said. “If the cyathia have fallen out, then the plant has passed its peak performance. Also, the lower leaves of the plant should look fresh and dark green. Yellow, faded leaves are indicators of plants that are nearing the end of their potential shelf life.”
Poinsettias are available with red, white, pink, peach, yellow, marbled and speckled bracts. Red poinsettias account for 80 percent of the sales in the United States.
Once the plant is taken home, Faust said it must be properly cared for to continue to look showy throughout the holiday season. Here are a few his suggestions:
- Place poinsettias in bright locations where the plants can receive as much light as possible.
- Keep poinsettias away from drafts, heating and air conditioning vents, as well as heaters.
- Avoid letting the bracts touch cold windowpanes because the transfer of outdoor temperatures can cause damage.
- Keep poinsettia plants moist but not soggy. Overwatering is a major cause of early leaf and bract drop in poinsettias.
- Maintain temperatures from 60 to 75 degrees.
- Do not fertilize the plants when they are flowering.
Proper care after the holiday season can help ensure poinsettia plants can bring cheer in the future:
- Prune the plant back to about eight inches tall around March or April.
- Keep the plant near a sunny window and continue to water it regularly.
- Move the plant outdoors once the nighttime temperature remains above 50 degrees.
- Fertilize the plant every two to three weeks during the spring, summer and fall with a well-balanced complete fertilizer, such as 10-10-10.
- Transplant the poinsettia in early June into a container two to four inches bigger than the original pot. Use a soil mix containing a considerable amount of organic matter, such as compost, leaf mold or peat moss. Pinch back the shoot tips or prune back the branches. Do not pinch back after August.
- Bringing the plant indoors, to a sunny location, when nighttime temperatures become cool, 55 to 60 degrees.
- Don’t expect these plants to flower like those grown inside of greenhouses. Most houses do not have sufficient light for the plant to grow big, beautiful flowers.
Growing poinsettias begins in July each year. The plants start to flower as the length of the night increases during the fall months until the flowers are fully mature in November.
Poinsettias are part of the Euphorbiaceae or Spurge family and are native to the west coast of Mexico. The milky white sap found in poinsettias was once used by the Aztecs as a fever medicine. The Aztecs also extracted a purplish dye from its bracts to use in textiles and cosmetics.
The poinsettia’s journey from Mexico to the United States began when Joel Roberts Poinsett, a South Carolina politician, served as the first U.S. ambassador to Mexico. Poinsett believed that agriculture was the key to economic development, so he facilitated the exchange of plants between the U.S. and Mexico. The poinsettia just happened to be one of the many hundreds of plants that were exchanged. Poinsett was honored by having the plant named after him. The name poinsettia continues to be used in most English-speaking countries, while the Mexicans refer to the plant as la nochebuena, translated as the holy night.
Last year, Faust traveled to a remote canyon in Mexico to observe wild poinsettias firsthand. In the wild, poinsettias grow up to 12 feet tall and are topped with just one flower. The plants are rather gangly shrubs that cling to steep canyon walls nestled in remote mountainous areas. This holiday season, Faust will be returning to Mexico to visit a small mountain town, Taxco, that holds an annual poinsettia festival that was initiated in the 17th century by Franciscan monks who first used the poinsettia to signify the blood of Christ.
Faust shares his passion for poinsettias by teaching Clemson students how to properly cultivate the plant in a greenhouse on campus.
Horticulture major Elizabeth Elmore from Columbia is a student taking Faust’s Horticulture 2100 Growing Garden Plants in the Fall class. In addition to learning other topics, the students are learning how to control diseases and pests in poinsettias, something Elmore said she believes everyone, especially people who sell poinsettias should consider.
“Monitoring for diseases and pests are key to maintaining attractive poinsettias,” Elmore said. “One pest growers should be sure to look out for is white flies. These flies are unsightly and can cause foliar damage to the plants at high populations. This damage can turn away potential customers.”
For more information regarding poinsettia plants, refer to the Clemson Home and Garden Information Center’s Poinsettia fact sheet (HGIC 1561 Poinsettia).