By John Fulton
The poinsettia is a plant that is native to Mexico, and has become the traditional potted plant at Christmas time. While many believe that the red, pink, or white color is the flower, it is actually called a bract. Bracts are colored leaves. The true flowers are there, but they aren't very showy.
Many of the improved varieties offered today last an amazingly long time. To keep them looking good and lasting, keep the room temperatures between 60-68 degrees (if possible) and with very high humidity. Temperatures over 75 are really hard on poinsettias, especially with low humidity. Try to place your poinsettia by a bright window just out of direct sunlight. Remove it from the window at night if there is a danger of chilling. Keep soil moisture at moderate and uniform levels, and never let the pot stand in water.
Reblooming poinsettias is a common goal, but bear in mind that this is one of the most difficult plants to succeed with. If you're a gambler, or a die-hard horticulturalist, here are the basic steps to improve your success.
After you are done displaying your poinsettia, gradually withhold water. The leaves should soon turn yellow and drop. Store the dried-off plant in a cool (meaning 50-60 degree), dry, dark, basement room until April or May. During this period, water lightly with just enough to keep the roots and stems from drying out too much.
When you bring the plant back up, prune stems to about six inches. Remove from the pot, take some old soil from the roots, then repot using a well-drained mixture. If there are several plants in the pot, separate and pot them individually. Use a pot that provides plenty of room. Water the plant well and place in a warm, sunny spot for renewed plant growth. You can put the plants outside when frost danger has passed, but be wary of direct sun in the hottest part of the day. You may have to repot the plant if it becomes rootbound. If you're into starting cuttings, you may have decent success by starting new plant from the shoots that appear on your old cut-back plant in the spring.
Keep the plant actively growing during the summer months by watering regularly and applying a complete liquid fertilizer every couple of weeks. As new shoots form, pinch them back so that two nodes (leaf pairs) remain on each. Stop pinching off shoots in August. Also, you may want to remove some of the weaker stems completely, allowing only a few of the stronger ones to develop. Control insects as they appear, and if plants become diseased they should be pitched.
Before cool weather in the fall, place the plant inside in a south window with full sun through the day. Watch the temperatures and moistures. Temperatures should be 60-65 during the day and 70-75 at night. Moisture should be moderate. Starting the last week of September, your plant should only be exposed to natural sunlight (this means no house lights after dark). Probably the best method is to put the plant in a closet overnight. Once the leaf color forms you can increase non-daylight light.
With these recommendations, and a little bit of luck, your poinsettia should be ready for the holiday season.