Questions on: Poinsettia

Ron Smith, Horticulturist, NDSU Extension Service

Q: I have had a poinsettia plant for about three months. I repotted it not too long ago and now there is very thick mold growing around the bottom of the pot. The mold has started spreading to the topsoil. This is puzzling to me because poinsettias don't need much water, so I know it is not overwatered. How do I get rid of the mold? Is the mold harmful to my plant? (e-mail reference)

A: This is a saprophytic mold, not a parasitic type. It is "digesting" the organic matter in the potting soil and on the surface of the pot. It will not hurt the plant. The best way to be rid of it is to scrub it off the container and loosen the soil in the pot with a cultivator. It doesn't take much moisture to get this kind of mold to grow, so I would suggest that you add another day or two between your current watering cycles to encourage drying. Moving the plant outdoors this spring, after the danger of frost has passed, will help you get rid of this problem.

Q: I have a large poinsettia Iím hoping to keep alive, but Iím not sure how. There arenít many red leaves left on the plant, but the soil is moist. Is there a way to keep it alive so it will bloom? (e-mail reference)

A: The lack of red leaves should not be a concern. Continue to care for the plant the way you have. If possible, keep it in a bright location. When the danger of a frost is over, move it outdoors where it can grow like a shrub. Take cuttings from the new growth this summer. Root and pot the cuttings. Bring the new plants and the mother plant indoors before the first fall frost and then subject them to short days (more than 12.5 hours of darkness) to initiate leaf coloration. You can leave the plants uncovered after coloration.

Q: I have a beautiful poinsettia plant in my window. I have two cats, but woke up this morning and found one dead. She loved plants and I had to chase her away a few times from the poinsettia. Could the plant have killed her? (e-mail reference)

A: I am sorry to hear about the loss of your cat. Poinsettias are not poisonous, but the alkaloids in the leaf tissue can cause irritation to the mucus membranes of the mouth and throat. It could very well have been that the plant was treated with a systemic pesticide that, when ingested by your cat, reached the lethal dose. Even if plants are listed as not being poisonous, pets and certainly children should be kept from ingesting them. My wife and I have three cats that we have had for more than a decade; we spoil them with affection and they spoil us in return. I have empathy with your unexpected loss.

Q: Are poinsettia plants poisonous to children or pets? (Email reference)

A: They are not poisonous to the extent of killing a child or pet. But, because it is a euphorbia species, some people are sensitive to the milky sap the plant produces. Some folks classify it as poisonous because of that sensitivity, others don't. Either way, it is not a good idea to ingest it. I'm told that the taste is repugnant enough that one couldn't eat much of it anyway.

Q: I have two poinsettias that nearly died after Christmas. We forgot to water them for over a month! As you can imagine, nearly everything died. After a lot of work, they are finally growing new leaves. My problem is that the new leaves aren't growing from the main stems; they are suckers. What should I do to get this plant to look like new and make it bloom again? (E-mail reference)

A: Continue caring for it as you have been. When all danger of frost is past, plant it outdoors in an eastern or northern location. Most poinsettias respond beautifully from such treatment. You can take cuttings from it this summer or bring it indoors and begin the short day treatment toward the end of September, to bring it in flower.

Q: My poinsettia was doing so beautifully outdoors this summer I couldn't bear to cut it back so I brought it inside before a hard freeze. It is now losing leaves. It is in a south window. What should I do? (Sioux Falls, S.D.)

A: It will eventually re leaf so donít worry. Be patient and keep it evenly moist but not soggy and in a south window.

Q: This spring we planted some Nashville and Newport shrub roses and weigela bushes in the landscape rock surrounding our house. They are planted on the west and northwest side of our country home and will catch all of the cold winter winds. We want to try to help them make it through the winter and are planning on using hay to cover them. However, we are not sure about the pruning. All of the shrubs did well. Should they be pruned back after they go into dormancy this fall? Also, how do you recommend pruning 3-year-old spirea bushes? (Aberdeen, S.D.)

A: I would hold off on the pruning this fall as they will not have time to heal sufficiently. Do your pruning next spring in late March or early April. Concerning the spirea shrubs, I would selectively prune out the oldest canes as far back as possible, but no more than a third of the canes.

Q: I received a beautiful poinsettia for Thanksgiving from my daughter. It has since begun to look very sickly and nearly all of the leaves have fallen off. What do I do now? I have been afraid to disturb it for fear it will die. (Litchville, N.D.)

A: Poinsettias are tougher today than ever before! Repot it if necessary and keep it in a south window. You should also get some houseplant fertilizer that promotes blooming. Summer the plant outdoors, take some cuttings to root, bring everything in this fall before frost and begin the cycle over again.

Q: Do you have a suggestion on how to get rid of what looks like white mold (on the red blooms) of my indoor poinsettia plant? (E-mail reference)

A: The white mold is likely cottony cushion scale. It would be very unusual to have white mold on a poinsettia grown as a houseplant. The air in winter is simply too dry to have it develop.

Dip a cotton swab in rubbing alcohol and rub it over the spots you are calling white mold. If I am incorrect and you do have a low-grade fungus, it is probably powdery mildew. In either case--white mold or powdery mildew--you are better off dumping the plant than trying to correct either problem.

Q: At Christmas in 1999 I received three poinsettia plants. They never do well indoors for me. The plants I had looked very bad, losing most of their leaves. So I said what the heck, and planted all three plants together outside. I never thought they would live, but the plant was beautiful this year and had wonderful color. Now with winter soon to be over, what should I do to take care of the plant? I have heard that they should be cut back, but how much should be cut and is there any other care I should worry about? (E-mail reference, Tampa, Fla.)

A: Poinsettias grown outdoors will tend to become leggy and unattractive, so the only care needed is to prune them to suit your tastes so they make attractive outdoor shrubs. Keep the soil on the slightly acid side with peat moss and fertilizing with ammonium sulfate. Toward the end of summer, thin the branches so that larger red-colored bracts may be produced around Christmas. Also, you can take cuttings while the shrubs are still vegetative and root them in peat moss quite easily, for your own houseplants next holiday season. Cuttings should be about 9-12 inches long.

Q: I bought a poinsettia for Christmas 1998 and put it in front of our south-facing picture window. It's had no repotting, no pruning, no special lighting. All I do is water it once in awhile with water from my goldfish tank.

The red began appearing just before Thanksgiving. It's good this plant decided to color up all on its own, because I'd never be organized enough to do the 12 hours of dark and light in the closet thing. Since we have cats, we cannot leave any doors shut in our house. They are much to nosey!

Maybe this plant had extrasensory perception and knew that I had planned on getting one of those pink mottled poinsettias this year and would have thrown the old one out. It colored up and I saved money and have had lots of enjoyment out of watching it grow and change. (Cooperstown, N.D.)

A: Thank you for the success story! Your house sounds like mine--giving in to the whims of the cats! We have four!

Q: This is the second year for re-blooming my poinsettia, so I think I can say I know how to do it now, ha.

The poinsettia is allowed to bloom all winter long and then is planted in the ground (in pot) after all danger of frost is passed. Due to vacations etc., it was probably late June before it got set out this year. It was brought back in late in September or early October due to late frost this year, placed in south facing window in back bedroom. This room is not used daily, but the door is left open, the shades are not drawn and we go in and out occasionally, so nothing special is being done about lighting (or lack thereof). This plant and one other I have started blooming in November. As an experiment, I cut part of it back as it had gotten so lanky. I was afraid of pruning the whole plant for fear it would inhibit bloom. This was done in the fall when I brought it inside. The new foliage came on the pruned branches and even when quite small, started blooming at same time as older foliage. I will try pruning it when I set it outside next summer and possibly setting into ground without pot. I think this will produce a fuller, better-shaped plant. In the meantime, we are certainly enjoying our second year of re-blooming with these two plants. Evidently, the fact that the bedroom has mostly natural lighting without electric light being turned on in evenings, except once in a while, is allowing the correct amount of night hours for the plant. (Hatton, N.D., e-mail)

A: I appreciate you sharing your learning experiences with me. Anyone who can re-bloom poinsettias two times is indeed an expert!

Q: I have a beautiful poinsettia plant that I transplanted to my garden this spring. It looks great now, but I am wondering how I can bring it back in the house. Will it bloom for Christmas? Also, do gladiolas have to be lifted in the fall? (Wahpeton, N.D.)

A: Basically, cut your poinsettia back to the height you want, bring it inside and give it long nights. And yes, lift the glads after a frost has blackened them.

Q. Can you tell me how to get a poinsettia to rebloom? (Bowdon, N.D.)

A. To get a poinsettia to rebloom it needs total darkness for about a 14-hour period from the end of September until early December. Put it in a dark closet or keep in a room that will remain dark from about 5 or 6 p.m. until 7 or 8 a.m. every day. The room's temperature is best kept from 60 F to 70 F, but day length is more critical for bloom.

Q. When do I bring my poinsettia in and put it in the dark? Also, how often should it be fertilized, and what kind of fertilizer? Should cannas be started in the house in the spring or put directly outside? (Wimbledon, N.D.)

A. The poinsettia needs more than 12 hours continuous darkness every 24 hours starting at the end of September. The top leaves should begin coloring up around Thanksgiving. A good, general-purpose liquid fertilizer should be applied once per month, following directions on the container label. Refer to the enclosed extension publication, "Poinsettia Care in the Home" (H-906), for more details.

Yes, start the cannas indoors in February. That way you can enjoy the flowers and foliage much longer when they get set out.

Q. I have had my poinsettia plant outside all summer, and it has grown a lot and looks healthy. I am wondering when I should start putting it in a dark place and for how long? Also, should it be fertilized? (Mayville, N.D.)

A. Enclosed is a publication on poinsettia culture, "Poinsettia Care in the Home," (H-906). Basically, the sooner you begin giving it "long nights"—that is more than 12 hours of darkness—the sooner it will set the colorful bracts. Generally, providing these conditions by Oct. 1 will yield a colorful plant in December.

Q. Have a 4-year-old poinsettia. Will put it outside this summer. Should I cut it back some? It bloomed for me without doing anything special. Thanks. (Bonesteel, S.D.)

A. Nice going! The plant obviously likes the environment you keep it in. Yes, plant it outside in late May on the east or north side. You can cut it back if you wish. It will grow beautifully outside this summer.

Q. I have a Keepsake azalea and could you possibly send me some information on how to care for it after it is done blooming. Also could I have information on caring for a poinsettia? Thank you. (Redfield, S.D.)

A. The term Keepsake azalea has no botanical meaning to me. It is likely a hybrid between Rhododendron obtusum and R. simsii.

These plants all require acid soil and water to thrive. I strongly suggest using rainwater, snowmelt or distilled water. They will last only one season if kept indoors; indefinitely if summered outside.

After the danger of frost is past, sink the pots into the sphagnum-peat-enriched soil on the north side of the house, mist with distilled water on hot, dry or windy days, and bring in before the first fall frost.

Q: This summer I planted last Christmasís poinsettia in the ground outdoors. This fall I repotted it and brought it into the house. How can I get it to bloom again? Itís a full, beautiful green plant.. (Montrose, S.D.)

A: Youíre going to be a little late to get it to rebloom by Christmas, but itís worth a try. Begin immediately by giving it short days. You can do this by covering the plant with a lightĖproof sack, box or bag for at least 13 hours. Many folks do this by covering the plant when they come home from work at 5 to 6 p.m., and uncover it just before they leave the following morning around 7 to 7:30 a.m. Do this every day until flower buds are evident (actually the bracts begin coloring up), then you can stop. It should take about six weeks for this to happen.

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