CORVALLIS, Ore. – Holding onto poinsettias after the holidays is good for the pocketbook but hard on the ego when you can’t get them to color up the next year.
Experts at Oregon State University Extension Service say now’s the time to start coaxing poinsettias back into color and bloom for December. Sensitive to day length, the poinsettia needs a certain minimum amount of darkness each 24-hour period to stimulate blooming in the winter. With the shorter fall and winter days in Oregon, the plant has a natural tendency to bloom in spring, when there are about equal amounts of dark and light.
If the plants are exposed to lights inside the home, they won't receive enough darkness to start blooming and could stay green through winter.
To make a poinsettia bloom in early winter, indoor gardeners simply need to adjust the amount of light and darkness to "fool" the plant.
In mid- to late October place your poinsettias in a completely dark area from 5 p.m. to 8 a.m. daily until red color starts to develop on the flowers or “bracts.”
This can take quite a while. People often forget to cover the plant one or two nights. Interrupting the darkness by even a few minutes may cause failure of the coloring.
Bring the plant to ordinary light after the bracts show color. You may have better luck if the bracts are almost fully expanded before bringing the plant out. Once the plant has large, colored bracts, the artificial light inside a house will not inhibit a poinsettia's blooms.
Here's a general time line for "coloring" the poinsettia:
Yellowing of foliage may indicate insufficient light, over-watering or lack of nitrogen. Generally, a slight correction of the environment will correct any of these symptoms.
After blooming, the plant’s bracts and leaves will begin to fall naturally. Discontinue fertilizing and reduce watering. Cut the plant back to 6 inches. Water only enough to prevent the stem from shriveling. When summer rolls around, repot the poinsettia if necessary.
When you see new growth, start watering regularly and feed every two weeks with a balanced (the three numbers on the label are the same) fertilizer. As they grow, pinch back stems to encourage branching. Grow it outdoors or as a houseplant. If grown outdoors, be sure to check for insect pests and treat if needed. Next autumn, start the cycle again.
About the OSU Extension Service: The Oregon State University Extension Service shares research-based knowledge with people and communities in Oregon’s 36 counties. OSU Extension addresses issues that matter to urban and rural Oregonians. OSU Extension’s partnerships and programs contribute to a healthy, prosperous and sustainable future for Oregon.
Kym Pokorny, 541-737-3380, [email protected]
Click photos to see a full-size version. Right click and save image to download.