By Michigan State University Extension
Having a poinsettia plant during the holidays is a tradition for many people, and some often wonder if it’s possible to get the plant to bloom again for next year. It is possible, but it just doesn’t happen if the plant is indoors. Poinsettias require very specific light conditions to allow the plant to make flowers again. This requires some management to get it to bloom for the holidays.
Poinsettias have been considered as a holiday plant in the United States since the 1820s. Its botanical name is Euphorbia pulocherrima, which makes it a member of the Euphorbia family. This is why the milky sap can be very irritating to people’s skin. Poinsettias are named for Joel Roberts Poinsett, the first U.S. Ambassador to Mexico. He brought the initial cuttings to the United States and introduced them to plant enthusiasts here. The plant is native to Mexico where it can grow from 2 to 13 feet tall and is considered a shrub or small tree. The most common colors for the bracts that we call flowers are red, orange, pink, pale green, cream, white and marbled.
Your poinsettia should be moved outdoors during summer, so it is important to keep it in good condition now. Often, blooms will last for months after January. The first important part is to remove the colored foil covering the outside of the pot. It traps water if it has no holes and plants can be marinating in several inches of water, rotting the roots. Poinsettias need to be close to a west or south window and receive some sun during the day. Michigan State University Extension suggests watering it when the top inch of soil is dry.
When all danger of frost has passed, usually the end of May, it’s time to find a location outdoors where the plant will receive strong morning sunlight. More sunlight makes the plant healthier. Cut the stems back to about 6 inches and make sure some leaves remain. As new shoots grow, the tips of the stems can be pinched periodically to make the plant bushier. This just involves clipping the very tip of the stem. Water and fertilize the poinsettia to stimulate growth. The plant should be removed from the container at the time of planting.
Dig up and repot the plant in the fall. You will probably need a bigger container. This needs to be done before nighttime temperatures get close to 40 degrees Fahrenheit. Once indoors, find a location where the poinsettia will get 14 hours of continuous, uninterrupted darkness and 10 hours of bright light. Some people will move the plant into a room where they will not turn on lights. Others will put it under a cardboard box for the 14 hours. If you turn on the light, even for a brief time, it can affect the production of flower buds. Even small amounts of light such as a street light, car headlights or the light from a TV can throw it off.
After two months of the long night-short day lighting, colored bracts will begin producing. The flower is actually the little “button” at the tip of the stem, and the petals are leaves called bracts. If your poinsettia was colorized or dyed, the flower color will be different from when it was purchased. Purple with glitter does not exist in nature.
When most people realize the amount of work it is to get another year out of their poinsettia and how inexpensive many plants are, the choice may not be to try to rebloom the poinsettia, but to buy again.