Every January, I receive questions on how to keep poinsettia plants and have them flower again next Christmas.
My best advice is to dump them in the compost pile as soon as you get tired of looking at them or when they start dropping their leaves. Leave the growing of Christmas poinsettias to growers of greenhouse crops who have both the knowledge and the facilities to produce quality plants in full bloom in time for Christmas.
The poinsettia is known as a short-day plant, meaning that it initiates its flower buds and red bracks when daylight hours are fewer than 12. If poinsettias receive more than 12 hours of daylight during the flowering period of long nights, they will not initiate flower buds or they will develop red, yellow or white bracks.
Interrupting the long night with a flash of light sufficient to read your watch by stops the flowering process. Simply turning on a light in the room where the poinsettia is growing, in the middle of the night, is sufficient to stop flower initiation. Commercial poinsettia growers remove the fuses that control greenhouse lights during the growing of poinsettias as a safety measure to prevent accidental lighting until the flower buds become visible and the bracks are highly colored.
If you are determined to prove me wrong by flowering your poinsettia again in December, keep your plant in full sun, well watered and fertilized at least monthly until July. In mid-July, repot the plant into a large container and prune back the tops to within four or five inches from the top edge of the pot. Don’t water or fertilize the plant again until it starts new growth. Keep it in full sun and fertilize every two weeks, never allowing the plant to wilt. To grow a poinsettia with large bracks, allow only one or two shoots to develop from each stem. The more stems you allow, the smaller the bracks.
Starting in mid September, cover the plant with a lightproof box starting at about 7pm. Between 7 and 8am the following day, uncover the plant. The plant needs a minimum of 121⁄2 hours of total darkness to initiate flower buds and colored bracks. Night temperatures should not be allowed to drop below 65 degrees.
Continue this routine until the plant stops growing and begins to form bracks and flower buds at the ends of the stems. As soon as visible buds form at the ends of the stems, stop using the general plant fertilizer and start using only fertilizer that contains nitrate nitrogen. Fertilizing with fertilizers containing ammonium after poinsettias have stopped growing will result in visible leaf scorch on the margins.
Clarification on Burning Christmas Tree Stems
Q: After reading last week’s column about Christmas trees, I had to write about about burning pine trees.
You said the “stem of the Christmas tree can be cut and added to the wood pile for burning in the wood stove or fireplace next winter.”
That is all wrong. The sap from the tree will cling to the chimney. Then you will have a chimney fire. Do not burn wood, such as pine, that has sap.
I was with the Eastport Fire Department for over 25 years.
–Art Tuers, Annapolis
A: As for burning pine, spruce or fir tree stumps, I burn them all winter long in my wood stove in my shop. I also make certain that I clean my chimney every year, and I only burn a hot fire and do not choke it down.
I, too, was a fireman, in New Hampshire until I came to Maryland in 1962.