By Ray Greenstreet
Poinsettias belong to the diverse genus Euphorbia that contains many other popular temperate and tropical ornamental plants. All Euphorbia species including E. pulcherrima (poinsettias) have specialized and often colorful leaves below the flowers that function like petals.
Poinsettias naturally bloom in winter, but under home or office conditions they may need encouragement. They grow best in a sunny window or outside while temperatures remain warm, but they dislike cold temperatures below 50 degrees. Day length is the largest trigger for flowering; to flower poinsettias should be in uninterrupted darkness for about 12 hours each night. Ideally, nighttime temperatures should also be 10 degrees lower than daytime temps. Cutting them back well ahead of flowering helps maintain a compact, rounded shape. Luckily, all that hard work has already been done by the time you see red, pink, white, or yellow poinsettias arriving in stores. All you need to do is keep them warm, water them when they are dry, and make sure the soil is drying out most of the way (but not completely) before watering again.
There remains a misconception that poinsettias are toxic and dangerous. While it would be inadvisable to ingest any part of the plant, actual risk of harm is quite low. Eating several leaves may cause an upset stomach, but that’s far from dangerous. The myth began with an inaccurate 1919 report from Hawaii. In the 99 years since, there has not been a single death from the plant. Based on chemical analysis of the leaves, a 50lb child would have to eat about 500 for them to be harmful. The leaves are also quite bitter and serves as a strong deterrent in itself. There are a number of possible medicinal uses for poinsettias, including the Aztec use of the plant to reduce fever, but the best advice remains to treat it as non-toxic but also non-edible.
Red is, of course, the classic color for poinsettias, but new colors, patterns, and even new bract shapes have been introduced at an increasing rate over the past few decades. The creation of new poinsettia hybrids like the Princettia and Luv U Pink series has only added to this diversity. Traditional deep reds may always be the most popular, but keep an eye out for the new and exciting varieties.
Painting or dying poinsettia leaves has also been trendy in recent years, but should not be confused with the results gained from breeding. There are increasing efforts to extend poinsettias into new colors, but there are no blue poinsettias (yet). Colorings applied either as paint or dyes will not return when plants bloom the following year.