First, a little history of the poinsettia, which goes all the way back to the Aztecs in Mexico. During the 16th to 18th centuries, the sap from the poinsettia was used to control fevers. Joel Robert Poinsett, who was the first U.S. ambassador to Mexico, was very interested n botany. In 1828 he found beautiful shrubs with large red flowers growing on hillsides of Taxco which we now know as poinsettia. He was the first to bring the plant to the U.S. Today poinsettias are the most popular Christmas plants even though most are sold in only a six-week period.
After you have chosen your poinsettia, make sure it is wrapped completely and properly because exposure to low temperatures, even for a few minutes, can damage the bracts and leaves.
Since poinsettias are living plants and growing conditions in the home or office are sometimes less than ideal, poinsettias need some sound care to keep looking festive. Here are some guidelines to keep your poinsettia healthy for the holidays
Place your plant in a sunny window or well-lighted area, but out of direct sunlight and warm or cold drafts. The colored foil often wrapped around the poinsettia pot may be decorative, but keep in mind "drowning" of roots is a common problem. Either remove this wrap or poke some holes in it letting water out so plants do not sit in water and roots are not able to get adequate oxygen. Check the soil every day. Keep your plant evenly moist. Overly dry soil may cause flowers to drop off. To help avoid overwatering poinsettias wait until the soil surface begins to dry slightly before watering again. However, don't let the soil completely dry out and become hard, however.
Fluctuating temperatures around the plant are another major concern. An optimum temperature range would be 60 to 68 degrees F. Temperatures above 75 degrees F can cause decline. Keep your plant out of warm drafts such as from heat ducts or radiators. Likewise, don't put the poinsettia near an entrance where it will constantly get a cold draft. Another related problem is excessively dry air.
Showy "flowers" of the poinsettia are actually modified leaves called bracts. The true flowers are found inside the colored bracts and are yellow in color. For a poinsettia to develop the colored bracts, the plant needs to have long nights. The critical day length is actually 12¼ hours. If longer, only leaves will grow. If shorter, the plant will begin to develop flower buds and colored bracts.
For many years, the poinsettia was considered to be poisonous. Extensive tests have proven this to be false. However, as with most plants, a child or pet could still have stomach pain if they were to eat poinsettias.
Purdue publication HO-73-w ("THE POINSETTIA)" gives much more information on how to care for your plant through spring, summer and fall and propagation of additional plants. Call your Extension Service or look up THE POINSETTIA, HO-73-W online.
Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange County.