January – March: Keep watering the poinsettia whenever the surface is dry.
April: Starting April 1st, gradually decrease water, allowing the to get dry between waterings. Be careful the stem does not begin to shrivel. This is a sign the plant is too stressed and is dying. In a week or two, when the plant has acclimated to this drying process, move it to a cool spot like the basement or a heated garage. You want to keep it at about 60 degrees F.
May: In mid-May, cut the stems back to about 4 inches and repot in a slightly larger container, with new potting soil. Water it well. Place the newly potted plant back into the brightest window you have and once again keep it at a temperature of 65 – 75 degrees F. Continue watering whenever the surface of the soil feels dry.
Watch for new growth. Once new growth appears, begin fertilizing every two weeks with a complete fertilizer. Follow fertilizer label recommendations.
June: More the poinsettia outside, pot and all. Keep it in a partially shaded location and maintain your watering and fertilizing schedule.
July: In early July, pinch back each stem by about one inch. This is to encourage a stout, well branched plant. If left unpinched, the poinsettia will grow tall and spindly.
August: By mid-August, the stems should have branched and leafed out. Once again, pinch or cut the new stems, leaving 3-4 leaves on each shoot. Bring the plant back indoors and back into your brightest window. Continue watering and fertilizing.
September: Continue regular watering and fertilizing. Make sure the temperature stays above 65 degrees F.
October Poinsettias are short-day plants, meaning their bud set is affected by the length of daylight. To re-bloom, poinsettias need about 10 weeks with 12 hours or less of sunlight per day. You will have to artificially create these conditions and it’s crucial that you be diligent.
Beginning October 1st, keep your plant in complete darkness from 5 pm to 8 am. Any exposure to light will delay blooming. Use an opaque box or material to block out light. Many people place their plants in a closest, but if light gets in though the cracks or if you open and use the closet, it will affect the bud set.
Move the plant back to the sunny window during the daytime and continue watering and fertilizing.
November: Around the last week of November, you can stop the darkness treatment and allow the plant to remain in the window. You should see flower buds at this point
December – Stop fertilizing about December 15th. Keep watering and treat your plant the way you did when you first brought it home in bloom. If all has gone well, it should be back in bloom and ready to begin the process all over again.