Poinsettias offer colorful holiday decorations

December 17, 2020

How Does Your Garden Grow?

By Sharon Daniels

We can thank South Carolina native Joel Poinsett when we enjoy what is probably our favorite plant for Christmastime decoration.

When Poisett was a special envoy to Mexico in 1822-23, he visited an area south of Mexico City and discovered what later became known in the United States as a poinsettia. In Mexico it is called Horde Nochebuena, Christmas Eve flower.

They are tropical plants, so if you bring poinsettias home this week, ask to have them wrapped well for transport and don’t let them sit very long in an unheated vehicle or they could start dropping leaves.

To choose plants, look first for healthy green leaves. Next, scan the real flower of any poinsettia, the cluster of small yellow ones in centers of the colorful bracts. Buy those which remain closed with no yellow pollen showing.

There are four types of poinsettias: the familiar ones with solid color bracts in pink, white, red, yellow or even purple; marble with two-tone bracts; jingle which has red or pink bracts with flecks of white or cream; and rose whose bracts curl slightly back and under, making them look like clusters of roses in full bloom.

We’ve been warned to keep poinsettias away from children and pets who might taste them, but the milky, sticky sap is mostly an irritant to skin and eyes, particularly for those who have a latex allergy.

Care is fairly simple. Water them so the soil remains evenly moist. Test by touching the soil surface and if dry, add some water but don’t flood the pot. Roots can rot if they sit in standing water. They prefer a room temperature of 60 to 70 degrees, and may react by dropping leaves if you place them in a chilly window or in a direct draft. Also don’t set them near a fireplace.

They can rebloom but the process is cumbersome. After bracts fade, cut stems just below “flowers.” When spring temperatures are regularly 50 degrees or above, set them in a protected place outdoors. In June prune again to about 6 inches tall and repot with fresh soil. Add a half-strength fertilizer every four weeks.

About the first of August, pinch an inch from each growing tip to encourage branching. Bring indoors before overnight temperatures fall below 60.

Rebloom requires 14-16 hours of uninterrupted darkness every night for eight weeks. A box in a closet works, but because even light from under a door can disrupt the process, cover the box with a blanket. A good schedule is 5 p.m. to 7 or 8 am., then give the plant bright but indirect sunlight each day. When bracts start to develop color, you can stop nightly covering.

We also can thank Joel Poinsett because he advocated for establishing the Smithsonian Institution to document North America’s natural resources, celebrate its technology and showcase the country’s relics.

Sharon Daniels is a Virginia Cooperative Extension Master Gardener volunteer.