Keep your Poinsettias Year After Year

January 2, 2018

By: Ron Kushner


Poinsettias are leafy plants, typically with dark green leaves topped with colored, modified leaf bracts which are often incorrectly considered to be flowers or flower petals. The real flowers are tiny, mostly berrylike in the center of each colored leaf bract.
The common name “Poinsettia” for this popular holiday season plant was given in honor of Joel Poinsett, a gardener, and botanist from South Carolina. He was the U.S. Ambassador to Mexico in 1825 where he found the native Mexican plants growing.
The botanical name is Euphorbia pulcherrima (you-FOR-bee-uh pul-CARE-i-muh). The genus name Euphorbia was given in honor of Euphorbus, a Greek physician in Africa in the 1st century, BC. The species pulcherrima means “pretty”. Also, take note that “poinsettia” is a four syllable word!
Contrary to widely circulated misinformation, poinsettias are not poisonous to humans or animals. If ingested in enormous quantities, only mild discomfort would be experienced.
When the poinsettia’s bracts age and lose their aesthetic appeal, there is no reason to throw it out or toss it into the compost. With proper care, it will re-bloom! The process can be a bit of a challenge but it can be done.
By late March or early April, cut your poinsettia back to about 8″ in height. Continue regular watering and fertilize with a balanced, all-purpose fertilizer. By the end of May, you should see plenty of new growth.
Place your plants outdoors after all chance of frost has passed, normally after mid-May. Night temperatures should be above 55 degrees F. Some morning sun is fine but the plants do best in indirect sun. Continue regular watering and fertilize every 2 to 3 weeks.
About June 1st, transplant the plants into larger pots, no more than 4″ larger in diameter than the original pot. Use any soil-less potting mixture sold in garden centers. Some pruning may be required during the summer to keep the plants bushy and compact. Late June or early July is a good time to do this but don’t ever prune after September 1st.
Poinsettias set buds and produce flowers as the autumn days get shorter. In their native Mexico, they naturally come into bloom during November or December, depending upon the individual cultivar.
Starting October 1st, the plants must be kept in complete darkness for 14 continuous hours each night, followed by 6 to 8 hours of bright sunlight daily. To achieve the required darkness, move the plants to a totally dark room or cover them with a large box. Stray light of any kind, such as from a street light or household lamp could delay or entirely halt the re-flowering process. Also, night temperature must not be lower than 60 degrees nor higher than 70 degrees.
Continue normal watering and fertilizing and the night-time darkness regime for 8 to 10 weeks and you should have colorful blooms for the holiday season.
Fertilizer is not necessary while the plants are in bloom. Water thoroughly, saturating the soil completely, allowing them to drain. Do not allow the pots to sit in water in saucers. If you see leaves or bracts wilting, water immediately.
Poinsettias thrive in humid air. In dry, interior environments, place pots on a pebble tray or mist the leaves frequently. Keep plants away from drafts, fireplaces and ventilating ducts.
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