Two plants are iconic for the winter holiday season, Christmas trees and poinsettias. Most people either have a fake tree they take down after the holidays and put back in the box or a formerly living tree that they leave on the curb or take to be recycled at the local Nature Center. We don’t have either because we have four cats. Who get into everything. Often.
We don’t have poinsettias, either, for the same reasons. Poinsettias (Euphorbia pulcherrima) are often just thrown away at the end of the season, but you can keep the plant and have it rebloom next year. The plant is a native of southern Mexico and is named after Joel R. Poinsett, the first U.S. ambassador to Mexico. He brought the poinsettia to the United States in 1825. While we mostly think of poinsettias as red, they can be white, pink as well as red and white. I have seen blue and green ones, too, but they were done with dye.
The flowers of the poinsettia are not the large red colored pieces of the plant. Those are called bracts and are just colored leaves. The flowers are the small yellow button-like structures at the center of the bracts.
Poinsettias are commonly thought to be poisonous, but laboratory studies have shown that the leaves, stems, bracts and flowers are not toxic to people or pets. However, if a leaf or stem is broken or cut, it oozes a white substance that may be mildly irritating to the skin. Wash off your hands or any part of your skin that gets sap on it. And if the sap gets ingested, it may cause a mild stomach upset.
While you have the poinsettia in the house, check the soil daily to determine whether or not the plant needs water. When the soil is dry to the touch, water the plant thoroughly. Water should flow freely out of the bottom of the pot. If you don’t have a tray under the plant, place the pot in the sink. If you do have a tray underneath, pour out the excess water. The root system can be damaged by sitting for long periods in saucers full of water. Bracts should remain attractive often through Valentine’s Day.
Most people throw out the poinsettia after the holidays. However, you can keep the plant and get it to bloom again next season. Keep the plant watered even when the bracts are not “blooming”.
In May, cut the remaining stems back to about 3-6 inches above the soil. You can repot the plant or separate the stems if there are several in the original pot. Use a pot with good drainage and use a quality potting soil that has been pasteurized to kill any diseases. Water completely.
Starting in the spring, fertilize every 2 to 3 weeks with a complete fertilizer (10-10-10) and follow the directions on the fertilizer label for flowering plants.
When the minimum outdoor temperature is consistently above 60 degrees (usually the first part of June in Iowa), it is safe to move the poinsettia outside to partial shade. Increase watering frequency when you see shoots beginning to grow.
The poinsettia needs to be pinched back to control height and to promote a more full plant. The first pinch should be done when the first shoots are several inches long, or around the first week of July. Remove the upper inch of growth on each stem, leaving 4 or 5 leaves per stem. Pinching promotes the plant to put out more branches and create a fuller plant. After pinching, that milky sap will be secreted, so make sure you wash the sap off your hands. You can also wash the sap off the plant with a gentle shower from a hose. A second pinching may be needed in August.
In order for poinsettias to produce flowers, they must experience days with less than 12 hours of daylight. Most varieties require 8 to 10 weeks of these short days to flower. For full color before December 25th, you need to start these “short days” in early October. If you want your poinsettia to bloom earlier or later, adjust when you start. Plants are at their best for 4 to 6 weeks after your target flowering date.
To start this “short days” phase, the plant must be in complete darkness from 5 PM to 8 AM which can be accomplished by placing the plant in a dark closet or in a light-proof box. Any light that the plant gets during the dark period can delay flowering, so make sure you aren’t using the closet that you will need to get into during the plants “dark” time.
Light is still needed for growth, so the plant should be placed in a sunny location from 8 AM through 5 PM. Water as needed and fertilize every week according to the fertilizer label until the bract color develops.
Once color is visible, it is not necessary to keep the poinsettia in complete darkness during the night. At this time, the plant will flower with any amount of daylight.
Doing all of these steps will keep your Christmas mood going all year long!
By the way… I apologize for the drawing at the top. I am not, nor have I ever been, an artist. And I was using a computer mouse… not the paintbrush and water colors from my schooldays!
This post was written by Eileen Loan on January 9, 2012