The colorful poinsettias that bring a bright note to gray winter days have been a holiday tradition since they were first introduced in 1825. They were brought into the United States by the first ambassador to Mexico, Joel Poinsett. These plants, also known as euphorbia pulcherrima, are native to Mexico and Central America. Though many are discarded with the Christmas tree after the holidays, they can actually be cared for as an indoor houseplant all year round and made to bloom again the next holiday season. They bloom in response to shortened days and long nights, which can be reproduced anywhere with a little work.
Place the plant in complete darkness for 12 to 14 hours a night starting around late September or early October. This will force the plant to bloom and the bracts or colorful leaves that surround the yellow flowers to change color. This process takes about 10 weeks. A box or a closet that will remain closed are a couple of options. Any light that is allowed to enter will delay the blooming process.
Move the plant to a location with bright, indirect sunlight during the day.
Water the plant regularly but only after the soil at the top of the plant feels dry to the touch.
Slowly decrease the amount of watering after it flowers until the colored leaves, or bracts, all drop. This will help allow the plant to survive until the next holiday season.
Store the plant in an area that stays at a constant 50 degrees F if possible, until it starts to warm up again in the spring.
Repot the plant in the same pot with fresh soil and start to water again, slowly increasing the amount and frequency of the water.
Fertilize the plant every two weeks to one month using a complete houseplant fertilizer. Stop fertilizing once the plant starts to bloom.
Cut the plant back in late summer to about three to five stems and let it regrow.