Getting your poinsettias to bloom again!

By Melanie Mathieson
Gardening Guru

After the Christmas season your poinsettia may start to loose its coloured bracts and look more like a regular house plant. When this happens there is no reason to throw it out. With proper care, dedication and a certain amount of luck, you can get your poinsettia to rebloom! Clip and save this column so you have the directions throughout the process.
As mentioned in an earlier column your poinsettia should be kept in a bright light and humid environment. Make sure to keep the soil moist but not soggy and remember to protect the plant from drafts. By late March or early April, cut your poinsettia back to about 8” in height. Continue to water regularly and fertilize your plant with a good water soluble all-purpose fertilizer, following the instructions and mixture stated for blooming houseplants. By the end of May, you should see vigorous new growth. Around June 1, you may transplant your poinsettia into a larger pot. Select a pot no more than 4 inches larger than the original pot. A soil mix with a considerable amount of organic matter, such as peat moss or leaf mould, is highly recommended. This is often packaged as a African violet mix. Whatever the label or type of soil, make sure you buy a good quality soil that has been sterilized. Remember to wear gloves if you have sensitive skin when handling your poinsettia for repotting or pruning. If you are allergic to latex you may want to have someone else handle the plant for you.
Once the weather warms up and the danger of frost passes and night temperatures average 55° F or above, you can place your poinsettia outdoors, where they can enjoy the warmer temperatures. Keep the poinsettia in its pot. Even though this plant grows in the wild in Mexico, do not transplant the plant directly into the ground in our region, as you most likely will kill it. Continue regular watering during the growth period, and fertilize every 2 to 3 weeks. Keep the plants in indirect sun and water regularly. As growth develops, cut or pinch back, leaving three or four leaves on each shoot. Repeat each time the plant sends out new shoots until mid-August. Then bring the plant indoors and set it in an area of bight light again and where the temperature will remain between 65 to 70°. Make sure not to prune your plant later than September 1. Check for insects once you bring the plant back into the house. Poinsettias can be very susceptible to whitefly. If you see small white flies you can apply an insecticidial soap or an indoor plant pesticide made with pyrethrine (made of daisies; it’s organic and safe if you don’t drink it). Most other insects, like red spider mites or aphids can be treated by giving the plant a warm gentle spraying of water in either the kitchen sink or bathtub. A gentle shower should wash all other insects away.
The poinsettia is a photoperiodic plant, meaning that it sets bud and produces flowers as the autumn nights lengthen. Poinsettias, grown in their natural habitats in Mexico, will naturally come into bloom during November or December, depending on the flowering response time of the individual cultivar. Timing to produce blooms for the Christmas holiday can be difficult outside of the controlled environment of a greenhouse. Stray light of any kind, such as from a street light or household lamps, could delay or entirely halt the re-flowering process. Follow the instructions listed very carefully in order to ensure the best results.
Starting October first, the plants must be kept in complete darkness for 14 continuous hours each night. This is the key to success. To accomplish this, you can move the plants to a totally dark room, closet or cupboard, or by covering them overnight with a large box or paper bag. Total darkness for 14 hours is essential so make sure where you put the plant each evening it is in total darkness. Also make sure that the night temperatures are between 60 - 70° F as temperatures outside of this range could also delay flowering. During October, November and early December, poinsettias require 6 - 8 hours of bright sunlight daily so make sure each morning you remove the plant from the darkened area. Continue with the normal watering and fertilizer regime.
As December approaches and after carefully following this program for 8 to 10 weeks, you should start to see the upper bracts changing colour. I hope with these tips and your careful following of the instructions you are rewarded with a colourful display of blooms for the holiday season!