The poinsettia thrives on indirect, natural daylight. Exposure to at least six hours daily is recommended. Avoid locations where the plant is exposed to direct sunlight, as this may fade the bract color. If direct sun cannot be avoided, diffuse with a light shade or sheer curtain.
To prolong the bright color of the poinsettia bracts, daytime temperatures should not exceed 70 degrees F. Avoid placing the plants near drafts, excess heat or the dry air from appliances, fireplaces or ventilating ducts.
Poinsettias require moderately moist soil. Water the plants thoroughly when the soil surface feels dry to the touch. Remove the plant from decorative pots or covers, and water enough to completely saturate the soil. Do not allow the poinsettia to sit in any standing water. Root rot could result which could kill the plant.
It is not necessary to fertilize the poinsettia when it is in bloom. However, a balanced, all-purpose household plant fertilizer may help maintain rich, green foliage and promote new growth after the holidays. Follow the directions on the fertilizer label.
Since poinsettias are sensitive to cold weather, frost and rain, outside placement during the winter months should be avoided. However, in mild climates, an enclosed patio or entryway may be suitable provided the night temperatures do not drop below 55 degrees F. Make certain the delicate bracts are well-protected from wind and cold rain. Chill damage will occur if temperatures drop below 50 degrees F., resulting in premature leaf drop. Exposure to frost for even a short time will usually result in the death of the plant.
Even if you don't have a green thumb, the poinsettia can provide enjoyment throughout the year as an attractive green foliage plant. When the bracts age and lose their aesthetic appeal, usually by late March or early April, cut the poinsettia back to about 8 inches in height. The amount you cut form the top of the plant will depend upon its shape; some plants will need more pruning than others to achieve a full, rounded canopy. After cutting, the plant will look quite stark, and while this is not a poinsettia's most attractive state, by the end of May you should see vigorous new growth. Pruning may be required during the summer to keep plants bushy and compact, but do not prune after September 1st. Keep the plants in indirect sun and water regularly.
After outside night temperatures average 55 degrees F or above, place your plants outdoors where they can bask in the warmth of spring and summer. Continue regular watering during the growth period. Fertilize every 2 to 3 weeks throughout the spring, summer, and fall months with a well-balanced, complete fertilizer.
Around June 1st, you may transplant your poinsettias into larger pots. Select pots no more than 4 inches larger than the original inner pot. A soil mix with a considerable amount of organic matter, such as peat moss or leaf mold, is highly recommended. If you wish, you may transplant the poinsettias into a well-prepared garden bed. Be sure the planting bed is rich in organic matter and has good drainage. Your poinsettias will do best in a protected area, preferably along a south garden wall. Immediately after transplanting, give the plants a thorough double soaking. Check plants periodically and treat for any insect pests that attack and colonize on the plants.
The poinsettia is a photo periodic plant, meaning that it sets bud and produces flowers as the Autumn nights lengthen. The plants will naturally come into full bloom during November or December, depending upon the flowering response time of the individual cultivar.
Timing the bloom to coincide closely with the Christmas holiday can be difficult without the controlled environment of a greenhouse. Stray light of any kind, such as from outside street lights or household lamps, could delay or entirely halt the re-flowering process. Starting October 1st, the plants must be keep in complete darkness for 14 continuous hours each night. Accomplish this by moving the plants to a totally dark room, or by covering them with a large box overnight. During October, November and early December, the plants require 6 - 8 hours of bright sunlight daily, with nighttime temperatures between 60 - 70 degrees F.
Temperatures outside this range may delay flowering. Continue the normal watering and fertilizer program. Follow this regime for 8 to 10 weeks. Although the re-flowering process takes more than a little perseverance for success, with care and attention you can enjoy the beauty of this traditional holiday, favorite for many season to come.