The poinsettia (Eupitorbia pulcherrima Willd.) is the traditional Christmas plant. It is native to Mexico and was introduced to the United States by Joel Poinsett, the first U.S. Ambassador to Mexico. In mild climates, such as Florida and California, the poinsettia is also grown in the landscape.
The striking beauty of the poinsettia is found in the showy bracts, which are specialized leaves, surrounding the true yellow flowers. Plants with red bracts are most popular, but plants with yellow, orange, pink, white, and variegated bracts are also available.
The newer cultivars of poinsettia, in addition to being very showy, have excellent keeping quality and stronger stems than older cultivars. When buying your poinsettia, choose a plant with well-expanded, well-colored bracts. Foliage should be medium to dark green with uniform coloring. Flowers should be present in the center of the bracts, but ideally still mainly closed with little pollen present.
(1) After you purchase your plant, do not expose it to chilling temperatures or cold drafts of air. If the temperature outdoors is below 50 F do not carry an unwrapped plant from the retail shop to your car. In the home or other place of display, avoid cold drafts and excessive heat from heating ducts, or large incandescent lamps. Temperatures of 70 F or below (down to 60 F) are desirable to retain best bract color. Large plants can be placed on the floor if light is adequate. Do not allow plants to make contact with windows, as cold glass may be injurious.
(2) Light plays an important role in retention of leaves on the plant. Place the plant in an area where it receives at least six to eight hours of direct natural or artificial light. A minimum of 75 foot candles is desirable where possible. This would be similar to the minimum Iight intensity required for good desk lighting in an office. Incandescent lights such as those found in most homes will give a truer, brighter bract color than most types of fluorescent light.
(3) Poinsettias can be displayed with other houseplants. The adjacent plants raise the humidity and allow poinsettias to last longer. Also, the regular houseplants can be spruced up for the holidays.
(4) Many commercial growers use non-soil mixes of sphagnum peat, pine bark, vermiculite, perlite, or similar ingredients. When plants are grown in such non-soil mixes, it is sometimes difficult to decide when the plant needs water. If there is no heavy component (sand or soil) in the mix and a plastic pot is used, the pot can be lifted to determine its weight. If the plant is heavy, there is usually plenty of moisture in the pot; if it is lightweight, the medium is dry and a thorough watering should be given. Moisture needs can also be assessed by feeling the growing medium in the pot. Water when the top of the growing medium is starting to feel dry, but do not allow too much drying. Slight wilting of the plant is not harmful, but avoid severe wilting, which will cause leaves and bracts to drop faster.
Water the plant thoroughly. Make sure a small amount of water drips through the drainage holes of the container. If the plant is wrapped with decorative foil, punch a hole in the foil beneath the pot to allow excess water to escape. The plant should be placed on a saucer to prevent damage to the furniture or carpet.
Do not water the plant too frequently when the soil or growing mix is already wet or this may result in roots suffocating from lack of oxygen, causing the leaves to wilt, yellow, and drop. A carefully chosen plant should remain attractive in the house for a minimum of eight weeks.
(5) Recent research has shown that poinsettias are not poisonous, but the plants are intended solely for ornamental purposes. Some people are allergic to the milky sap and may develop a rash when exposed to the sap. Avoid breaking the leaves and stems, as this will release the sap. It is wise to keep any houseplant out of the reach of small children and pets.
Re-Flowering for Next Year
(1) It is easier to discard a poinsettia after the bracts fall and buy a new plant next year. Commercial growers work hard to produce high quality plants for the public. The newer cultivars usually hold their flowers (bracts) for several months instead of just a few days or weeks. If light is lacking, the leaves usually drop before the bracts. Adequate light results in longer leaf and bract retention. After the bracts have faded and the plant is no longer attractive, watering frequency can be reduced and the plant should be held in a cool location, such as 50 F to 60 F. However. if the foliage is still attractive, grow the plant on as a foliage plant.
(2) In March or April, cut back the original stems to within four to six inches of the soil surface. If the plant is too large for the pot, shift to a larger container using a good potting mixture from a local florist, greenhouse, nursery, or garden center. If the original pot contained more than one plant, these can be separated and planted in individual pots if desired.
(3) About May 15, well after danger of frost is past, the plant can be moved outdoors to a partially shaded (not heavy shade) area of the flower garden or shrub border and the pot placed in the ground to the rim. The soil in the area should be well drained so that overwatering and poor drainage are not a problem. A large heavy pot need not be buried to the rim.
If a well-lighted, moderate temperature indoor location is available where the plant can be cared for, it can be kept inside most of the time. However, plants benefit from some outside exposure. A soft summer rain shower can really perk up a plant. Do not place plants where hot, drying winds and reflected heat can cause damage.
(4) Water as needed, avoid extremes of underwatering or overwatering. Apply a complete house plant fertilizer through the summer at a rate and frequency recommended by the manufacturer. Occasionally lift the pot and prune off roots that grow into the soil. If this is not done, too much root growth into the soil may make it more difficult to later move the plant indoors. Between July 15 and August 15, long shoots will develop. The terminal portions of these shoots should be cut off to induce branching. These excised tips, three to five inches long, can be used for cuttings if additional, young plants are desired. Take the cuttings in early morning, dip the basal ends in a rooting powder (rooting hormone) and plant in a pot or styrofoam cup (punch drainage holes in bottom) filled with moist vermiculite or one-half sphagnum peat and one-half vermiculite or perlite. Cover with plastic film and place in a shady, warm location. Keep moist, but gradually aerate by cutting holes in the plastic film and, when cuttings are rooted (three to five weeks), transplant to larger pots.
If no new cuttings are taken in the summer, and your interest is only in re-flowering the old plant, keep tips of the longer shoots pinched back to induce branching. Try to shape the plant into a rounded, bushy plant, making the last pinches approximately August 15 to August 25. If too many shoots result, carefully prune off a few excess branches. Plants can be transplanted to a size larger container if they appear to be outgrowing the pot. If the plants appear to be in proportion to the pot, simply leave the plants in the old pot.
(5) Lift the pots from the flower garden or shrub border in late September. Bring the plants inside and place them in a sunny window. Avoid “burning” light, but do not give too much shade or leaf drop, spindly growth, and sparse blooming may result. Follow previously mentioned watering practices.
Use a house plant fertilizer during this indoor forcing period, following the manufacturer’s recommendations
relative to rate and frequency. Do not apply more fertilizer than recommended.
Poinsettias must have long, uninterrupted nights to bloom and in order for the plants to flower for Christmas, they should be kept in complete darkness from 5:00 p.m. to 8:00 a.m. each night, beginning in late September, placing them back in the sunny window each day. This can be as simple as placing the plant every evening in a light-proof box or in a closet. Follow this procedure until good bract color is showing (often prior to Thanksgiving). If possible, the temperature should remain between 60 F to 70 F. Whether you prefer trying to re-flower your poinsettia or purchasing another the following Christmas, enjoy the poinsettia’s flaming beauty each year. This living symbol of a joyous season is a colorful part of the American Christmas tradition.
Extension Ornamentals/Floriculture Specialist