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Poinsettias have a hard time thriving indoors because they seldom get enough light in the home environment.
Holiday plants: To stay or go
By David Zlesak
From eNews, January 10, 2008
The holidays have come and gone and we're faced with the task of putting away the decorations.
Seeing brightly colored bracts (those modified leaves that turn color near the center) on poinsettias or a few colorful petals left on a cyclamen usually sways me to keep them around a bit longer. Having a blooming plant of almost any sort helps make a winter day in January more bearable.
But the time eventually comes to decide: adopt these plants into your "family" of houseplants or send them on their way. Here are some tips to help make your decision about four major holiday plants.
Difficult to keep as houseplants: Poinsettia (Euphorbia pulcherrima) Poinsettias are challenging to keep as houseplants because they seldom receive enough light in the home environment to thrive. They are rather susceptible to root rot which is exacerbated by water stress (over-watering or allowing pots to dry out too much between watering). They are also very susceptible to whiteflies. Unless one has a very bright window or greenhouse, poinsettias typically limp along, seldom bloom in subsequent years, and generally do not thrive.
In the past I've enjoyed using poinsettias as annual foliage plants in sunny areas of garden beds or in large pots on the deck. Harden poinsettias off as any other houseplant or bedding plant before moving them to sunny outdoor conditions. Cyclamen (Cyclamen persicum) Cyclamen bloom over an extended period of time. In order to keep young flower buds forming and developing in the crown of the plant, grow in a cool location with bright light. Removal of spent flowers can also encourage more flowers to develop. When deadheading, grab the spent flower stem securely and pull it completely off from the crown of the plant. Cyclamen typically go dormant after flowering.
It is very difficult in the home environment to grow a compact, high quality cyclamen plant. Typically, light levels are not high enough and result in puny-looking plants with elongated leaf petioles falling over the edge of the pot as they reach towards light.
Easier to keep as houseplants: Norfolk Island pine (Araucaria heterophylla) Commonly sold around the holidays as an indoor, living Christmas tree. Plants are typically sprayed with glitter, decorated with small bows and other ornaments, and have their pots covered with festive foil or other plastic pot covers. Norfolk Island pine is probably the most amenable conifer to home conditions.
Freezing conditions may kill tender new growth or the whole plant. Plants grow best in warm, uniformly moist, well-draining soil, and high humidity. Under low humidity, tips of new growth and older needles can become brown. Prolonged periods of low humidity can also result in older branches completely dying. You can increase humidity by misting, putting bowls of water on radiators and other warm places, or using humidifiers, which can also benefit plants such as ferns and African violets.
Christmas cactus (Schlumbergera _buckleyi) Probably the easiest holiday plant to grow in the typical home. Temperature and day length (actually perceived as night length) are the two main factors that trigger flowering in this plant.
At temperatures in the 50sF plants typically set and develop flower buds under both short and long photoperiods. If the temperatures are in the 60s to mid-70s, at least 14 hours of night are necessary for flowering. At temperatures above the mid-70s, Christmas cactus typically does not flower. Lower temperatures will help blooming flowers last longer. In addition, providing extra water during flowering will help keep flower buds from dropping and allow flowers to open well and last longer.
David Zlesak is an assistant extension professor with the University of Minnesota Extension Regional Center Andover.