Poinsettia: Compost Pile or Windowsill?

Kari Mazzaferro, Kanawha County Extension Agent

So is your poinsettia still alive after Christmas and wonder what to do with it now? Most gardeners and growers recommend to “use them and lose them.” Following the yearlong schedule to reflower a poinsettia can be frustrating and rarely results in a pretty specimen (unless you and your poinsettia are moving to southern Florida where you can grow it as a shrub) – but it is possible. As Master Gardeners, I know this challenge is something you are willing to try and gain bragging rights for doing. Here is a brief outline of after Christmas care:

▪ From January to late March/April, water as any other houseplant in winter (sparingly).

▪ In April/May, cut the stems back 4-6 inches. Repot into 1 to 2 inch larger pot, water and place in a sunny indoor area.

▪ When new growth starts, fertilize with an all-purpose fertilizer.

▪ When night temperatures are above 55° F and all danger of frost has passed, place outside in slightly shaded area. Fertilize every 2 – 3 weeks.

▪ From June to September 1, prune every few weeks to keep the plant bushy and small. For the last prune, keep 3 to 4 leaves per stem. If you do not prune, the plant will be very leggy and tree like – which can be interesting too.

▪ Bring plants in by September 1 or before night temperature drops below 55° F. Keep in a sunny area and water as needed.

▪ CRITICAL STEP: Starting October 1 plants need 10 weeks of 12-14 hours of continuous DARK. During the day place in sunny window and water and fertilize as needed.

Poinsettias are short-day, photoperiodic plants. In tropical areas, they flower naturally in December as the days grow shorter. However, any stray light, even a nightlight or streetlamp, can give off enough light to interrupt, or even cancel, the flowering schedule. How you manage to achieve 14 hours continuous darkness is up to you. There have been many inventive ways have been developed by gardeners. In greenhouses, this “night” is often achieved with the use of black curtains wired to computer programs and occurs automatically. Most gardeners and professional growers cover the plants at dusk (5 p.m.) and uncover them at 8 a.m. It is also advisable to watch for insects such as spider mites, whiteflies and scale.

An urban myth exists that poinsettias are toxic to humans. University research has proven this old wives' tale to be false. According to POISINDEX Information Service, a 50-lb. child would have to eat more than 1.25 lbs. of poinsettia bracts (about 500 to 600 leaves) to exceed the experimental doses (POISINDEX is the primary resource used by most poison control centers). The white sap may irritate sensitive skin and cause nausea and vomiting if eaten in large quantities, but is not fatal. In fact, the poinsettia may be more beneficial than toxic. In 1992, NASA research scientists included poinsettia on the list of houseplants most helpful in removing pollutants from indoor air.