WOOSTER, Ohio — Poinsettias are America’s favorite Christmas ornamental plant.
Whether you prefer traditional red, white, pink or any of the marbled and speckled varieties now available, you want to make sure you select the right poinsettia and take the proper care so it can thrive during the holidays and beyond.
“When you go to the store, inspect the plants carefully and make sure that you don’t see leaves that are dried out, that are sagging, that have obvious signs of damage,” said Luis Canas, an entomologist and expert on greenhouse ornamentals with Ohio State University’s College of Food, Agricultural, and Environmental Sciences.
“Then approach the plant, gently turn the leaves and take a look at the underside of the leaves, which is where a lot of the insects live. It will be very obvious to you if there are signs of insect presence there.”
One of the most common insects found on poinsettias are called white flies. If present, they will be on the underside of the leaves.
White flies are very tiny, pure white, and scaly in appearance.
“The quality of the plants found in Ohio is really good and rarely you find these insects, but it’s always good to check,” said Canas, who works with Ohio’s large greenhouse industry to find economical and environmentally friendly ways to get rid of white flies and other pests of ornamental plants.
In addition to the leaves, it is also important to check the plant’s roots, Canas said.
“Grab the plant and gently tap on the pot so you can turn it upside down and check the roots,” he said. “The roots need to be of a whitish color; that’s a sign that they are healthy. If they look too brownish or even blackish, and when you touch them they peel off, that’s a sign that the root system is not very healthy. Even though these plants will last between two and three weeks, they may end up dying because of this problem.”
Canas also recommends you pay attention to poinsettias that are not watered properly at the garden store and avoid buying them.
Poinsettias are native to Mexico and Central America and don’t like cold weather. When you take your plants home, avoid placing them too close to windows or places where they will be exposed to a cold breeze.
Additionally, keep them away from heater vents to avoid drying the leaves.
“Poinsettias will do well where there’s a lot of sunshine,” Canas said. “Be careful with watering. One of the biggest problems taking care of plants is overwatering. My recommendation is to let the soilless media dry before irrigating again.”
Canas said poinsettias usually come well fertilized from the greenhouse, but if you want to keep them longer, it’s a good idea to use a slow-release fertilizer to keep them healthy and strong.
“If you ever see insects on the leaves, it’s easy to manage them using insecticidal soap,” Canas said. “It usually comes as a prepared fix. Gently and thoroughly spray the leaves so the insects will die. This type of product can be used inside the house.”
You can enjoy the beauty of poinsettias well after the holidays with the right amount of care.
“Poinsettias can be kept all year round. A lot of people are surprised to hear that,” Canas said. “If they are watered and fertilized properly, they can grow for a long time. In fact, they can grow into large trees.”
As they grow, poinsettias will need to be repotted into a larger pot. Also, to make them turn color, they need many hours of darkness.
“That’s difficult to achieve at home, but it can be done,” Canas said. “In August or September, put them in the basement or another dark place. They will need 14-16 hours of darkness a day until they turn color.”
Examine the soil daily, and when the surface is dry to the touch, water the soil until it runs freely out the drainage hole in the container.
If a saucer is used, discard the water that collects in it. Do not leave the plant standing in water.
Overly wet soil lacks sufficient air, which results in root injury. A wilted plant may drop its leaves prematurely, so check the soil frequently.
Plants exposed to high light and low humidity require more frequent watering. If wilting does occur, immediately water with the recommended amount, and 5 minutes later water again.
If you obtain a poinsettia for your home, place it near a sunny window where it will have the most available sunlight. A window that faces south, east or west is better than one facing north.
Do not let any part of the plant touch the cold windowpane because this may injure it.
To keep the plant in bloom, maintain it at a temperature of 65 to 70 degrees during the daylight hours and, if possible, move it to a cooler place at night. Because root rot disease is more prevalent at temperatures below 60 degrees, do not put the poinsettia in a room colder than this.
Avoid exposing the plant to hot or cold drafts, which may cause premature leaf drop.
Poinsettias can be reflowered the following Christmas, but unless a yearlong schedule of care is observed, the results usually are not good.
For such a schedule, continue normal watering of the soil until the first of April, then allow it to dry gradually. Do not let it get so dry at any time that the stems shrivel.
Following the drying period, store the plant in a cool (60 degrees), airy location on its side or upright.
In the middle of May, cut the stems back to about 4 inches above the soil, and either replant in a pot 1 to 2 inches larger in diameter or shake old soil off the roots and repot in the same container, using a new soilless mix.
Many good commercial potting mixes are available. Choose one that is not very finely textured.
Using soil from the garden can introduce disease to the plant. Water the soil thoroughly after potting; wait five minutes and water again. Then put the plant near the window that is exposed to the most sunlight.
Keep the plant at a temperature of 65 to 75 degrees, and water when the surface of the soil is dry to the touch.
After new growth appears, fertilize every two weeks with a complete-analysis, water soluble fertilizer at the rate recommended on the label for flowering plants.
In early June, leave the plant in the pot, move it outdoors, and place it in a lightly shaded location. Continue watering and fertilizing the plant while it is outdoors.
Pinch each stem (remove 1 inch of terminal growth) in early July. Then, between Aug. 15 and Sept. 1, cut or pinch the new stems back, allowing three or four leaves to remain on each shoot.
After this second pinch, bring the plant indoors and again place it near a window with a sunny exposure. If the plant is not pinched, it will grow too tall and be unsightly.
Keep the plant at a temperature of 65 to 70 degrees at night and continue watering and fertilizing.
Poinsettias are short-day plants, which means they flower about 10 weeks after the daylight shortens to about 12 hours or less. Therefore, to have the plant in full flower by Christmas, keep it in complete darkness between 5 p.m. and 8 a.m. from the first part of October until Thanksgiving.
During this period, any kind of light exposure between 5 p.m. and 8 a.m. will delay flowering.
A closet, opaque box or opaque cloth will keep the plant in darkness during those hours. Remember to put the plant near a sunny window in the daytime.
Continue fertilizing the plant until mid-December.
Various reports over the years have led the general public to believe poinsettias are toxic to humans; however, this has not been authenticated.
Research conducted at The Ohio State University and other institutions has proved the old wives’ tale that poinsettias are poisonous to be false.