Poinsettia- Euphorbia Pulcherrima
By Judson Reid
Cornell Cooperative Extension
Master Gardeners

There are several, colorful flowering plants available to keep the indoor winter gardener busy. Besides removing some of the doldrums of being cabin fever bound for another four months, some of these plants can offer an interesting challenge. Over the next few weeks, Master Gardeners will be writing about Christmas Cactus, Jade Plants, and perhaps begonia and cyclamen, as well as this article about poinsettia. If you have a special request for future articles, contact the Master Gardeners at the Yates County Cornell Cooperative Extension. Most past Master Gardener articles can be accessed from our web page at http://www.cce.cornell.edu/yates/MGIndex.htm or by calling the Cooperative Extension Office.

From tropical Central America, the land of the ancient Maya, comes a perennial plant that we associate with one of the highest holidays of Christianity and Western culture. It is not the small yellow flowers that people cherish, but the bright bracts that surround them. Their colors range from red through pink, apricot, and cream, to white. These bracts accompany the small flowers; thus we should manage the plant with the goal of inducing flowers. The modern poinsettia is superior to earlier varieties. With good growing skills, some poinsettias may retain their colorful bracts through the Christmas season and on into March. The plants themselves can be grown to larger sizes and to bloom repeatedly every Christmas season.

First, let's look at how to care for the newly purchased plant to maintain bright color throughout the first holiday season. When purchased, poinsettias should be in prime condition for decorative use in the home. They should be well-shaped plants, exhibiting dark green foliage with bracts free from defects.

Poinsettias use a lot of water. Check soil moisture by digging down a half-inch under the surface with the fingertips. The soil there should be moist. If the soil feels dry, carefully add room temperature water until it begins to run out the pot's drainage hole. Allow the pot to drain thoroughly. Do not allow water to remain beneath the pot in the saucer or wrapping. Too much water will cause the roots to rot and the plant will deteriorate. Do not let the plant get so dry that the leaves begin to wilt. Cold air drafts from cold windows, fans, and forced air return system ducts may cause too much evaporation from the leaves and bracts, resulting in the plant's inability to keep up with the water uptake needed to replace lost moisture (transpiration loss). Excessive dryness may be one cause of pre-mature leaf and flower bract drop.

Once a week during bloom, add a balanced liquid fertilizer mix for indoor flowering plants being sure to follow the labeled directions. Once, with older varieties of poinsettia, fertilizer was not recommended during bloom periods. But with newer varieties, bloom can be extended with the addition of fertilizer. The fertilizer solution should be applied directly to the soil and not allowed to come in contact with foliage.

Excessively hot, dry air from radiators or heating ducts will reduce the life of the plant, as will cold air drafts. Temperatures between 65 and 70 degrees Fahrenheit are ideal during the time of holiday display. It is not necessary to move poinsettias into a cool room at night. Place the plant in good light but not direct sun.

The destiny of poinsettias after they have lost their colorful bracts does not have to be the compost bin. Coaxing this plant to flower during the holiday season next year is an exciting challenge that requires detailed attention from the indoor gardener. After the holiday display season is over, gradually withhold water. The leaves will then yellow and fall. This will induce dormancy. Allow the tropical immigrant rest by storing in a cool place with temperatures about 50 to 60 degrees until spring. Sparingly water, without fertilizer, just enough to keep the roots from drying out.

In spring, place the plant in a warm room and prune the stems back to about 6 inches above the soil. If there is more than one plant in the pot, divide and repot them at this time. Next, place the plants in a bright sunny window until frost danger is past as in late May. Repot the plant with a garden soil mix that contains at least 25 percent composted organic matter. Sink the pot outdoors in the garden where it will get some wind protection and where it will receive sun most of the day. Light shade during the hottest part of the summer afternoon is desirable. Lift the pot occasionally to keep roots from growing into the surrounding soil. As new shoots develop, cut them back to allow two nodes or pairs of leaves to remain. Do not pinch back shoots after mid-August.

Keep the plant in good growing condition by watering and feeding regularly during the summer. Add a complete liquid fertilizer about once every two weeks. Before the weather turns cool, well before killing frost, bring the plant indoors and place it in a bright, sunny window.

Poinsettias form flower buds when the daylight hours are less than 12 hours. Beginning the first of October, protect the plants from light by placing them in a dark closet between 5:00 PM and 8:00 AM daily. This is very important! Exposure to even the slightest amount of artificial light during this period will inhibit flowering. For this reason, some people opt to cover the plant every night with a heavy bag or cardboard cover. Remove the cover at about 8 a.m. each morning. After 40-60 days of this treatment, the plants can be kept in normally lighted rooms. Make sure the plant receives no additional light until colored bracts and flower buds are visible. Carefully following the above steps will induce the plant to flower during December. Failure of the plant to bloom during the Christmas season will probably be the cause of insufficient darkness as required above.

Poinsettia plants may be started from cuttings as well. However, fully grown plants are so inexpensive that most indoor gardeners would be best advised to purchase new plants rather than try to start their own.

A colorful piece of natural heritage from the land of the Maya is ours to behold this December. Nurturing the poinsettia to flower after a year of slumber is a challenge for the inside gardener when all else outside is covered with snow and ice. It brings a degree of satisfaction and accomplishment. However, there is always the opportunity to say the heck with it and run out and buy new ones.

Note: All Euphorbiaceae contain whitish sap that is a skin irritant. Avoid contact with any material that oozes from damaged tissue.

For all your lawn and garden questions, call the Master Gardeners at the Cooperative Extension office 315-536-5123 leaving your name, question, phone number and a time we may return your call with the results of our research. If you are interested in becoming a Master Gardener, a new class will be forming in January. Call the Extension Office for details.