A Greener View: Poinsettias may bring insects or diseases this holiday season
Dec 14,2007 00:00 by Jeff_Rugg

Q: We have had poinsettias for years and they have often lasted well into the new year; however, this year we got a lemon. It has small white insects flying around it when it is bumped. I moved it to a room all by itself as a quarantine. I don't want to throw it away, but I am afraid the flies will infest my other houseplants.

A: Although poinsettias are easy to grow, they can have problems. Any crop that is grown in large quantities can have insect or disease outbreaks. The worst insects to control in your home are whiteflies and spider mites. Both are pests on poinsettias; you should look for them before you buy the plant.

Do not use insecticidal soaps on poinsettias, because they are more likely to kill the plant than the pests. Spider mites can be washed off with water from the shower. White flies can be controlled with a pyrethrum-based insecticide or malathion.

I would maintain the quarantine except for brief times, right after the treatments, when the plant can be set out as a display. Because poinsettias are treated as annuals and thrown away within a few weeks after the holidays, I would throw this one away sooner (if not immediately) rather than allowing my other plants to be infested. Then you can avoid having to treat more plants with insecticides.

If you bought it from a discount store, you probably won't get much satisfaction attempting to return it or trying to complain. A reputable grower will stand by their plants, and will possibly give you a discount or a new plant rather than lose you as a customer.

Instead of getting another poinsettia, consider one of the several other plants that make great indoor decorations in the winter. Try cyclamen, azaleas, hydrangea, miniature rose, orchids, African violets, anthurium and any others that your florist recommends. Every house should enjoy fresh flowers all winter long.

Q: We were given a Christmas cactus and told it was a bromeliad. We couldn't find any care instructions. Can you help us?

A: The Christmas cactus is not a bromeliad, but it is more like a bromeliad than other cacti. In nature, they are similar to many bromeliads because they are epiphytic plants that grow on trees and other plants in South America. Epiphytes develop along branches without taking any nutrition from their host plant. There are three species of these jungle cacti used as houseplants - one that blooms in the fall, one in winter and one in spring. They get their common names during the holidays in which they are sold.

Their botanical names have been changed a few times in recent years, so let's just stick to their common names. The Thanksgiving cactus is actually the most commonly one sold, even for Christmas. Look at the flattened stem to tell them apart. It looks like a leaf, but these cacti do not have leaves. The Thanksgiving cactus has several long, saw-tooth projections on the edge of the "leaf." The true Christmas cactus usually has four rounded bumps on each stem segment. The Easter cactus has four to six wavy scallops on the edge. On all the species, the ends of the stems can have some small cactus spines.

Except for inducing them into bloom, everything else about the three cacti is the same. They make great houseplants because they live long and are disease and insect resistant. They do well with minimal care and even seem to bloom better if left to become root-bound in the pot.

On a tree branch, the soil they grow in is made up of loose organic matter. In a flowerpot, they can grow in African violet mix that is sold in bags or in a mixture of bark pieces, peat moss and a little potting soil. Even though they are cacti, do not use a cactus planting mix. Keep the soil moist except when forcing them to bloom.

Fertilize monthly during the summer using a fertilizer that promotes blooming. They can be moved to a shady outdoor location during summer. The best time to repot them is when they are not setting buds or blooming. Let them become pot bound before moving them up one pot size. They can be potted in clay or plastic; the best pot is a hanging basket.

Cooler fall temperatures and shorter days in the fall will induce the Thanksgiving and Christmas cacti into bloom. The Thanksgiving cacti will bloom in late November until the New Year. Christmas cacti bloom from late December through March. If these cacti are grown in a warm room (higher than 65 degrees) that has plenty of evening lighting, they might not bloom. Give them about six weeks after being moved to a cool, dark room or closet each evening, and they will set buds. Kept in a room that is always around 55 degrees, they might bloom without a short day length. Easter cacti will bloom if they receive cool temperatures under 65 degrees - lighting does not matter.

Keep the soil a bit on the dry side while flower buds are forming. After you can see the tiny buds, you can go back to the normal lighting and watering. Keep them cool (around 60 degrees), or else the flower buds may drop.

Being from South America and growing on trees might lead you to think they need to be in full sun. They need bright light all year long, but they can get sunburned if they are moved to a full sun location. An east window or near a south or west window will be bright enough.

Flowers are formed on the ends of the branches where the main vein hits the end of the line. Sometimes there is only a single bud, while other times there is a cluster of buds. The flowers have a series of petals that form a tube about 3 inches long. They can be red, pink, purple, orange and white. Easter cacti have a more limited selection of colors in the red and pink range.

These cacti are among the easiest plants to propagate. In May or June, cut off a piece of stem with at least three sections. Leave it out during the night; therefore, the end can develop a callous. Insert the cutoff section about 1 inch deep in moist perlite or sand. Keep the container covered to produce a lot of humidity and place it in a shaded location. They will root in about two months. When the roots are 1 to 2 inches long, repot the cutting into a new pot. Several cuttings can be planted into the same pot.

These cacti are easy to grow, and carefree houseplants that are worth trying to grow in your home.

E-mail questions to Jeff Rugg at info@greenerview.com.

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