Pointers for purchasing the right poinsettia this holiday season

I would like to purchase some poinsettias and need some advice on selecting good plants and caring for them. My friend told me to avoid this plant because poinsettias are poisonous, and I have a cat.

— Marci Carlos, Chicago

Poinsettias are traditional Christmas plants that will last throughout the Christmas season and beyond when healthy plants are purchased and properly cared for. Many businesses will have them for sale now, so they will be easy to find. The decorative part of a poinsettia is not its flowers but the cluster of colored bracts (modified leaves) that come in red, pink, white, yellow or multicolored.

Poinsettias contain a white, milky sap that is only mildly toxic to cats and dogs and can cause nausea and vomiting (rarely diarrhea) if enough leaves are eaten. It is unlikely that a pet or child would end up being poisoned because of the large amount of plant material that would need to be consumed. The sap has an irritating taste and effect on the tissues of the mouth which makes eating a large volume of foliage unlikely. Frequent contact with latex sap of poinsettias may cause a mild, short-lasting skin irritation and some people may be more sensitive than others. I used to have a cat that would chew on the leaves of any poinsettia I brought home — she never got sick but did enough damage to the plants that I decided to stop buying poinsettias. Cleaning up the sap that dripped on the counter was another problem after she chewed on the leaves.

Choose plants with dark green foliage all the way down to the top of the pot while avoiding plants that have fallen or yellowed leaves. Ideally, you vshould not be able to see the top of the pot. Plants with pale green leaves may not have been fertilized enough. Poinsettias that have been displayed or grown too close together can end up with some yellowed or damaged leaves. Avoid buying plants that are wilted as this stress can shorten the display time of the plant. If the plants are wilted and the growing medium is moist then there may be a problem with root rot. Look for insects under the leaves. Check the maturity of the poinsettia by looking at the flowers, which are located above the colored bracts. If the flowers are green or red-tipped and fresh looking, then the plant will hold color longer than if yellow pollen is covering the flowers.

It is very important to sleeve your new poinsettia before you take it home if temperatures outside are below 60 degrees Fahrenheit. Exposure to low outside temperatures for even a few minutes can chill or even freeze the plants, causing the leaves to droop and fall off. The sleeve will also protect the plant from breaking while it is being transported. Take the plants straight home after purchasing and avoid leaving them in a cold car as you run more errands. Once you get the plants home, promptly remove the protective covering, which can also damage the plants if left on too long.

Poinsettias like lots of bright, indirect sunlight. They are sensitive to extreme temperatures, so it is best to keep them away from cold drafts and heat vents. The foliage should not touch cold windows. Your poinsettia will not do well if placed near a busy entrance where doors are constantly opening and closing. Daytime temperatures of 65 degrees work well for prolonging the display of the colored bracts, though this is not practical in most homes. Water the plants thoroughly when the growing medium is dry to the touch. If the pot is wrapped in foil or sits in a decorative container without a drainage hole, remove it prior to watering. Make sure that your poinsettia never stands in water. There is no need to fertilize poinsettias during the holiday season.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.