CORVALLIS, Ore. — Holding onto poinsettias after the holidays is good for the pocketbook but can be discouraging when the plants don’t color up the next year.
Beginning in mid- to late October, place poinsettias in a completely dark location from 5 p.m. to 8 a.m. daily until the bracts begin to show red color.
Experts with the Oregon State University Extension Service say now is the time to start coaxing poinsettias back into bloom for December. Sensitive to day length, the plant needs a minimum number of dark hours each day to stimulate flowering.
In Oregon, with its short fall and winter days, poinsettias naturally want to bloom in spring, when the amount of darkness and daylight is about equal. Indoors, if they are exposed to household lights, poinsettias won’t receive enough darkness to trigger blooming and may stay green through winter.
To encourage early winter blooms, gardeners can adjust the plant’s light exposure to “fool” it into flowering.
Beginning in mid- to late October, place poinsettias in a completely dark location from 5 p.m. to 8 a.m. daily until the bracts begin to show red color. Interrupting the darkness by even a few minutes can prevent coloring.
Once the bracts show color, move the plant into normal light. You may have better results if the bracts are nearly full-sized before bringing the plant out. After they are colored, artificial light indoors will not stop poinsettias from blooming.
Timeline for poinsettia care
- Mid- to late October: Begin giving poinsettias long nights (darkness from 5 p.m. to 8 a.m.). Cover with a cardboard box or black plastic bag, or place in a dark closet.
- Mid-November: Bracts should begin showing color.
- Early December: Color should be nearly complete. Plants can return to normal light.
- December through February: During the bloom, keep plants at 60 to 70 degrees. Poinsettias are sensitive to cold. Provide as much sunlight as possible during the day. Water thoroughly, allow excess water to drain, and never let the pot sit in water.
Leaves may wilt if plants are too dry, too wet or exposed to drafts. Fertilize once a week in winter with a water-soluble fertilizer at half strength or less. Over-fertilization may cause leaf drop. Yellowing leaves may signal insufficient light, overwatering or lack of nitrogen.
After blooming
When bracts and leaves drop naturally, stop fertilizing and reduce watering. Cut plants back to about 6 inches tall. Water only enough to keep stems from shriveling.
In summer, repot if necessary. Once new growth appears, water regularly and feed every two weeks with a balanced fertilizer. Pinch back stems to encourage branching. Grow outdoors in warm weather or indoors year-round. Check for insect pests if kept outside.
Next autumn, repeat the dark-light cycle to bring color back for the holidays.
Previously titled Start now to get color from last year’s poinsettias in time for the holidays
