Carl Hoffman, University of Minnesota Extension Horticulturist
Be it reasons relating to the economy, an elevated environmental consciousness, or merely a reason to wear a new Snuggie™, we are lowering the temperature in our homes. We can easily compensate for the cool temperatures, but what about our plants?
As we enter the holiday season, many of us plant lovers like to use blooming plants to brighten and add seasonal cheer to the interior of our homes. Nearly all of the holiday favorites will perform well for a while, but then will begin to languish.
We are fortunate, however, that there are some blooming holiday plants that actually thrive in cool, or even cold, temperatures. Generally, temperatures above freezing, but below 50° F are considered cold, and temperatures between 50° F and 65° F are considered cool. Even some plants, like the poinsettia that prefer warmer temperatures will do quite well in a cooler environment if they are kept from cold drafts and are not overwatered.
Photo 1: A bench full of solid and bicolor Cyclamens. Carl Hoffman.
There are not many of us that keep our homes below 50° F, but if we did, cyclamens would be happy. The florist cyclamen, Cyclamen persicum, prefers night temperatures of 40° to 50° F and daytime temperatures below 65° F. These plants, with their large backswept petals in colors ranging from pastel pinks and lilacs to deep red and snow white, make beautiful, showy accent plants. The flowers are borne on upright stems that extend above attractive heart-shaped, silver mottled leaves. To prolong the blooming period, select a plant that has only a few flowers open, but many buds.
Cyclamens grow from tubers. They will rot easily if improperly watered so they should be watered from the bottom or, when watered from the top, use care to keep water from the crown of the plant. Allow the surface of the soil to dry slightly before you water, but do not wait until the plant begins to wilt. If placed in a room with cold to cool temperatures, bright light and when watered properly, cyclamen plants can be expected to remain attractive for up to two months.
Photo 2: Azaleas in perfect bloom stage for bringing home. Carl Hoffman.
Indoor azaleas (Rhododendron sp) with their masses of double or semi-double flowers in colors including white, pinks, salmons, reds and bicolors make a commanding holiday accent. With optimum temperatures of 45° to 55° F at night and up to 68° F during the day, azaleas will remain attractive for a month or more. When selecting an azalea plant for your home, do not be tempted to purchase a beauty in full bloom, but rather one that has a few flowers open and color showing in most of the buds. Azaleas need to be kept constantly moist and should be watered thoroughly whenever the soil in the pot feels dry to the touch. Azalea plants will drop their leaves if allowed to get too dry or if they are placed in a room with low humidity. For maximum performance, place your azalea where it receives at least four hours of bright, indirect light each day. An indoor azalea in full bloom is truly a living bouquet.
Orchids immediately bring to mind the tropics and warm temperatures, and thus are often overlooked when we are looking for cool temperature plants. However, orchids are an extremely diverse group of plants and there are representatives that will fit nearly every indoor condition, including cool temperatures. Once considered humid greenhouse plants that were difficult to grow under home conditions, there are species that actually require less care than some of our more common indoor plants. Improved breeding techniques have increased their availability and lowered their cost so that we can now readily enjoy these exquisite, long lasting flowers in our homes.
Photo 3: Paphiopedilum Satin Smoke.Jayme Hennek, Stearns County Master Gardener
There are at least seven genera of orchids that are classified as cool temperature orchids. Of these, I suggest that you try a Cymbidium or Pahiopedilum orchid for the holidays. A Cymbidium orchid plant in bloom with a huge spray of beautiful waxy flowers will make an outstanding accent or gift. There are both standard and miniature forms of Cymbidiums. Their narrow leaved foliage and large sprays of flowers need room, making the miniatures a better fit in most homes. Paphiopedilum or lady slipper orchids are terrestrial orchids and require less light than many of the other orchids. There are two main groups of Paphiopedilums: those with variegated or mottled leaves which require warmer temperatures, and those with green leaves which require cool growing conditions. Their beautiful flowers with their distinctive pouches may last two months or more under good conditions. Because Paphiopedilums grow naturally on the forest floor, they require a potting medium that contains some peat moss with the bark, and less light than do the Cymbidiums.
Photo 4: Christmas cactus in full bud. Carl Hoffman.
The Christmas cactus (Schlumbergia) is a beautiful plant that enjoys bright indirect light and cool temperatures, particularly when in bloom. Warm temperatures or drafts will cause the flowers and buds to drop prematurely. Purchase a plant that has many buds that are showing color and then place it where it receives bright light without high temperatures. Purchasing a Christmas cactus can be a long time investment as I have seen specimens that have been in families for 30 years or more. Hybrids have been developed that produce flowers in colors ranging from red, pink, magenta, white and even yellow. They are not true cacti, but are epiphytes similar to many bromeliads and orchids. The soil should be kept moist, but allowed to dry slightly between waterings.
Christmas cactus plants can be frustrating because the flowering period is affected by both day length and temperatures and it may be difficult to get them to bloom during the holidays. To initiate flowering, they require short days of less than 12 hours of light and temperatures of less than 68° F. At temperatures of less than 55° F, the buds will form regardless of day length. If your room only drops to 60° or 65° at night, you need to cover the cactus or put it in a dark closet for at least 12 hours each night to trigger blooming. Unfortunately, a plant grown at temperatures above 70° F probably will not flower regardless of the day length.
Norfolk Island Pine
As I was walking through a favorite greenhouse, I decided that I would be remiss if I did not include a non-blooming plant, the Norfolk Island Pine (Araucaria), on my list of cool temperature holiday plants. This conifer with its whorls of flat branches covered with short, dark green needles can be an accent plant even may even serve as a replacement for the family Christmas tree.
Norfolk Island Pine can be a beautiful focal plant in your home if you have a place where it receives bright light for at least part of the day. They will tolerate lower light for a while, but if not returned to bright light, the branches will droop and the new growth will be weak and pale colored. The most common problems Norfolk Island Pine face indoors are browning needles and dropping lower branches. Usually they can be attributed to hot dry air, low humidity, or allowing the soil to dry excessively before watering. Too much fertilizer can also contribute to needle drop and branch loss. It can be difficult to control the humidity in the home, but careful watering will help compensate for low humidity. Keep the soil moist, but not saturated, and water the plant whenever the soil surface feels dry. Like many of our indoor plants, the lower light intensity and the cooler temperatures of winter make it imperative that these plants are not overwatered.
We can readily see that a home with cool room temperatures need not be a home without blooming plants during the holidays. Well known favorites like cyclamens, azaleas and the long time favorite Christmas cactus welcome the cooler temperatures as do some of the newcomers like orchids. Of course, we can always add the "enjoy and toss" plants like poinsettias, hydrangeas and mums for more temporary bursts of color.
For more information on growing these or any other indoor plants go to http://www.extension.umn.edu/gardeninginfo/