Poinsettia plants (Euphorbia pulcherrima) remain one of the most popular holiday flowers. The familiar red flowers have been joined by even flashier colors. (Actually, what we think of as poinsettia flowers are not really flowers at all. They are modified leaves called bracts. The bright bracts are designed to attract insects to the tiny yellow flowers in their centers.) Hybridizers have expanded the range of colors from the familiar red to pastel yellow and vibrant bi-colors. Because poinsettias have been forced into bloom, they need some extra care, to keep them in bloom throughout the holidays.
Besides their general care, one of the most common questions about poinsettias after Christmas is “How can I care for my poinsettia so that it will bloom again next Christmas?”. While this can be done, it's a very fussy, exacting process and since the plants are not that expensive, you might just choose to start fresh next year.
For those of you who are undaunted, the process for saving your poinsettia and getting it to rebloom begins with the care you give it the first season.
When You First Bring Your Poinsettia Home
Light - Place it near a sunny window. South, east or west facing windows are preferable to a north facing window. Poinsettias are tropicals and will appreciate as much direct sunlight as you can provide.
Heat - To keep the poinsettia in bloom as long as possible, maintain a temperature of 65 - 75 degrees F. during the day. Dropping the temperature to about 60 degrees F. at night will not hurt the plant. However, cold drafts or allowing the leaves to touch a cold window can injure the leaves and cause premature leaf drop. If you've ever seen a leggy poinsettia in bloom, with only a couple of sad looking leaves hanging on, it was probably exposed to temperatures that were too cool or to extreme shifts in temperature.
Water - Water the plant whenever the surface feels dry to the touch. Water until it drains out the bottom, but do not let the plant sit in water. Wilting is another common cause of leaf drop. A wilted plant can be revived and salvaged, but it will take another season to improve its appearance.
Humidity - Lack of humidity during dry seasons, in particular winter, is an ongoing houseplant problem. If your home tends to be dry and your poinsettia is in direct light, you will find yourself watering frequently, possibly every day.
After Christmas Care
January - March: Keep watering the poinsettia whenever the surface is dry.
April: Starting April 1st, gradually decrease water, allowing the soil to get dry between waterings. Be careful the stem does not begin to shrivel. This is a sign the plant is too stressed and is dying. In a week or two, when the plant has acclimated to this drying process, move it to a cool spot, like the basement or a heated garage. You want to keep it at about 60 degrees F.
May: In mid-May, cut the stems back to about 4 inches and repot in a slightly larger container, with new potting soil. Water it well. Place the newly potted plant back into the brightest window you have and once again keep it at a temperature of 65 - 75 degrees F. Continue watering whenever the surface of the soil feels dry.
Watch for new growth. Once new growth appears, begin fertilizing every two weeks with a complete fertilizer. Follow fertilizer label recommendations.
June: Move the poinsettia outside, pot and all. Keep it in a partially shaded location and maintain your watering and fertilizing schedule.
July: In early July, pinch back each stem by about one inch. This is to encourage a stout, well branched plant. If left unpinched, the poinsettia will grow tall and spindly.
August: By mid-August, the stems should have branched and leafed out. Once again, pinch or cut the new stems, leaving 3-4 leaves on each shoot. Bring the plant back indoors and back into your brightest window. Continue watering and fertilizing.
September: Continue regular watering and fertilizing. Make sure the temperature stays above 65 degrees F.
October Poinsettias are short-day plants, meaning their bud set is affected by the length of daylight. To re-bloom, poinsettias need about 10 weeks with 12 hours or less of sunlight per day. You will have to artificially create these conditions and it's crucial that you be diligent.
Beginning October 1st, keep your plant in complete darkness from 5 pm to 8 am. Any exposure to light will delay blooming. Use an opaque box or material to block out light. Many people place their plants in a closest, but if light gets in though the cracks or if you open and use the closet, it will affect the bud set.
Move the plant back to the sunny window during the daytime and continue watering and fertilizing.
November: Around the last week of November, you can stop the darkness treatment and allow the plant to remain in the window. You should see flower buds at this point
December - Stop fertilizing about December 15th. Keep watering and treat your plant the way you did when you first brought it home in bloom. (See instructions, above.) If all has gone well, it should be back in bloom and ready to begin the process all over again.
Getting a poinsettia to re-bloom is not an easy process, so don't be disheartened if you don't have success your first try.
The Bottom Line on Poinsettia's Being Poisonous
For years poinsettias have had the bad reputation of being poisonous. They certainly are not meant to be eaten by humans, pets, or livestock and ingesting poinsettias would probably cause some stomach upset, as would eating most any houseplant. However poinsettias have undergone extensive testing and there is no evidence that they are toxic or unsafe to have in the house. They are also safe to put into the compost.
You Should Still Use Caution when Handling Poinsettias
A more likely problem to watch out for is contact dermatitis. Euphorbias, the plant family that includes poinsettias, exude a milky sap when broken. Think of milkweed, another common Euphorbia. Many people are sensitive to this sap, which can cause an itchy rash. Be especially careful not to rub your eyes after touching the plants. To be safe, wash your hands after handling a poinsettia plant and try to avid pinching or pruning them with your hands.
They're beautiful, they're safe, and they say Christmas. The only remaining question is whether to save them from year to year.