The Euphorbia pulcherrima, or poinsettia, is widely celebrated as the quintessential holiday plant, yet many people mistakenly treat it as disposable once the season ends. This tropical perennial, native to Mexico and Central America, is capable of thriving year-round and can be encouraged to display its vibrant, colored bracts again. Keeping this plant healthy requires a cyclical approach that mirrors its natural growth phases, moving it from indoor survival to outdoor growth and back to a controlled environment for re-coloring.
Immediate Post-Holiday Care
Once the holidays conclude, the poinsettia enters a period of transition and rest. Maintaining a steady indoor environment is paramount to its survival. The ideal daytime temperature range is 65°F to 70°F, with slightly cooler temperatures at night, but never falling below 50°F.
Place the plant in a location that receives bright, indirect light, such as a window facing east or south, ensuring the leaves do not touch cold glass. Keep the plant away from temperature extremes, including cold drafts from doors or windows and direct heat sources like radiators or furnace vents. Fluctuations in temperature can cause leaf drop during this post-holiday adjustment period.
Proper watering is a frequent challenge for indoor poinsettias. Water the plant thoroughly only when the soil surface feels dry to the touch, about 2 to 3 inches down. Ensure the pot has adequate drainage holes, and never allow the plant to sit in standing water, as this is the primary cause of root rot. Fertilization is suspended until new growth appears, signaling the start of the active growing season.
Spring and Summer Growth Cycle
As the days lengthen, typically starting around March or April, the plant signals the beginning of its active growth phase. When the colorful bracts begin to fade or drop off, it is time for the first major pruning. Cut back all stems to a height of 6 to 8 inches, leaving a few leaves or nodes on each stem to promote new, bushier growth.
After pruning, the plant can be moved to a slightly larger container, using a well-draining potting mix, if it appears root-bound. Resume a regular watering schedule and begin the fertilization regimen. Apply a balanced, water-soluble houseplant fertilizer monthly from spring until late August to support the development of new foliage.
When all danger of frost has passed and consistent nighttime temperatures remain above 55°F (usually late May or early June), the poinsettia can be moved outdoors for the summer. Choose a location that offers bright morning sun and partial shade during the intense afternoon heat to prevent leaf scorching. To encourage a dense, compact shape, pinch back the tips of the new stems (removing about an inch of new growth) every four to six weeks until late August.
Managing Light to Induce Coloration
The process of coloring the bracts depends on manipulating the plant’s sensitivity to light, a phenomenon known as photoperiodism. Poinsettias are “short-day” plants, requiring a specific duration of uninterrupted darkness each night to initiate the color change. This strict regimen must begin around the last week of September or the first week of October, about eight to ten weeks before the desired holiday display date.
The plant must receive 13 to 15 hours of complete darkness every day. A common method is placing the plant in a light-proof closet, a basement, or under a thick cardboard box from approximately 5:00 PM to 8:00 AM. Even a small source of light, such as a streetlight or a crack of light from a door, can interrupt the process and prevent coloration.
During the remaining nine to eleven hours of the day, the poinsettia must be returned to a location with bright, natural light. Continue to water the plant as needed, but suspend the fertilization schedule. The daily cycle must be maintained rigorously for six to eight weeks, or until the first signs of color appear on the bracts.
Maintaining the Colored Bracts
Once the bracts have colored up (typically late November or early December), the artificial light treatment can be stopped. Move the plant to its final display location, where it receives bright, indirect light. The colorful bracts will last longer if the ambient temperature is slightly cooler, ideally kept between 60°F and 70°F during the day.
Avoid placing the colored poinsettia near drafty windows, exterior doors, or heat vents, which can cause the bracts to quickly drop. Watering frequency should be slightly reduced from the summer growth phase, allowing the soil to dry out more between waterings. Resume the fertilization schedule only after the colorful bracts begin to fade, completing the annual cycle of care.