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How to care for those holiday houseplants

Poinsettias (left) and cyclamen (bottom) are among the houseplants that are staples of holiday decorating.

FRANK PERRY/AFP/Getty Images

Poinsettias (pictured) and cyclamen are among the houseplants that are staples of holiday decorating.

Many houseplants that bloom in December have become staples of holiday decorating, including azaleas, Christmas cactus, cyclamen, kalanchoe, paperwhites, Phalaenopsis orchids, amaryllis, and, of course, poinsettias.

Warm and dry modern houses, however, are a trial for most houseplants, including Christmas plants, which are happier in drafty old homes with un-insulated windows. If you are going to discard the plants after blooming, don’t worry about providing ideal conditions. However, if you want to keep them longterm, consider setting them up in a cool, sunny area, such as a porch or sunroom, to be brought out for display when company arrives.

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Don’t put plants near a radiator or on a TV set or they won’t even last through Christmas. Most have received enough feeding from the professional growers to glide through the holidays without more fertilizing. Careful watering, though, will prolong flowering.

Poinsettias

These euphorbias aren’t exactly made of plastic, but they are treated with chemicals to keep them compact, and engineered to bloom for up to six months, longer than most of us would like. What we think of as flowers are really colored leaves.

When buying plants, look for the true flowers, which are tiny yellow buds in the center of the flower-head. They should not be showing pollen. Let poinsettias dry out between waterings but water them immediately if the leaves begin to wilt. Misting is also beneficial.

Poinsettias should be discarded after flowering, but if you like a challenge cut the stems back to 4-inch stumps after the leaves have fallen and water them very little. In May, move them to larger pots with some new compost and increase watering and start fertilizing. Thin the new growth to five stems. They can spend the summer outdoors until the end of September. Then comes the hard part: You must cover them each evening with black polythene bags so they get exactly 14 hours of complete darkness until their unveiling the next morning. This will add a glum note to your decor, and if you forget to cover them for even one evening, your plants won’t color up. After eight weeks of this, treat them normally and they will bloom for Christmas.

Paperwhites

These fragrant narcissus bulbs are usually grown on top of a bowl of pebbles covered with water that just touches their basal plates on the bottoms. This is where the roots will sprout, winding quickly through the pebbles to anchor themselves.

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Some people find the smell of traditional white paperwhites too strong and prefer the more softly scented yellow varieties. Give them the sunniest spot you can so they don’t grow too tall reaching for the light. They will probably flop anyway, unless you tie them up. Discard them after blooming.

Cyclamen.

Cyclamen.

Cyclamen

Most homes are too warm to keep these as long-term houseplants. With care, though, you can keep the little flowers with their elegant swept-back petals in bloom for several months. They like to be in a cool, bright, north window where they won’t get direct sunlight, and should be moist at all times. Like African violets and gloxinias, cyclamen will rot if their leaves and crowns become wet, so immersing the pots just up to the soil line in a sink or bowl of tepid water for 10 minutes is the best way to water.

Most people discard cyclamen after they bloom. To try to keep them, reduce watering and stop feeding them to induce dormancy until midsummer. Then re-pot them with fresh soil mixture, making sure the bulb-like corms are one-third above the soil line, and resume watering and fertilizing. Put these in a north window where temperatures remain between 50 and 60 degrees after their summer outdoors.

Christmas cactus

Both the winter-blooming Christmas cactus and its popular cousin, the spring-blooming Easter cactus, have willing dispositions and flat arching stems that terminate in colorful flowers. They make the best long-term houseplants on this list, so don’t throw them out. Instead, to get them to re-bloom next year, decrease moisture to almost nothing after they finish flowering so they can have a rest period. Then trim the ends of the stems to increase branching (and flowering), and move them outdoors in a shady spot from June until frost is predicted. They form buds in response to shortening daylight, so keeping them outdoors as long as possible helps set their flowering clock. Back indoors, keep them dry-ish and cool until they bloom again, then increase watering. If your plants have scalloped stems instead of stem margins with pointed projections, don’t expect them to re-bloom for Christmas. They are Easter cactus.

Carol Stocker can be reached at carolstocker@gmail.com.

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