Poinsettias are floral favorites during the holidays, with beautiful red, white or pink blossoms and deep green foliage. The plant most associated with the winter holiday season is native to Mexico and grows best outside in areas where the temperatures stay around 60 degrees overnight. They can survive in overnight temps less than 60 degrees, and will even tolerate a very light frost, but these beauties prefer heat. Plant your poinsettias in sunny, wind protected areas of your garden or in a bright, draft-free room in your home.
Plant your poinsettia in potting soil for optimum results. Plant them in a container and then sink the container in your garden during the summer. Dig a hole that fits around the container, plus 2 inches added for depth. Place the pot in the hole and fill in around it with potting soil, not garden soil. You can also keep the poinsettia in a sunny location inside your home or on your patio.
Keep the poinsettia soil moist, but not soggy. To much water will lead to root rot and too little will cause the plant to dry out and drop its leaves. Poinsettias enjoy growing in a greenhouse where the humidity levels are higher. If you’re growing poinsettias in containers outside the ground, do not let them sit in drainage water. After watering, discard any water that fills the container’s saucer.
Maintain even temperatures around the poinsettias if you’re growing them indoors. Do not place the plants adjacent to heat vents or on a drafty window sill.
Help your poinsettia bloom at Christmas by keeping the plant in total darkness for at least 14 hours of the day for 6 weeks before the holidays. You can keep the plant in a darkened closet, cover it with a box or black material. Expose the poinsettia to at least 4 hours of direct sunlight each day during this period.
Prune the poinsettias after the flower bracts begin to fade, usually in February or March. Cut the stems back to about 8 inches tall with only one or two leaves on each branch. After pruning, cut back on the water. Let the top inch of soil in the container become dry between watering times. This is the dormant season for poinsettias.
Increase the water levels for your plant in late April or early May. Fertilize with 12-12-12 or 20-20-20 every third watering for vigorous growth by the first of June.
Move your poinsettia plant outside in June, if you like. This is also a good time to re-pot your plant with fresh potting soil. In mid-July, pinch back the branches about 3 inches to promote dense growth. Fertilize with half-strength every second watering.