Christmas cactus and thanksgiving cactus require cooler temperatures and need to be watered less frequently in the fall for buds to develop.
Flowering plants are always welcome gifts that help make the holiday season more festive and meaningful. Many of these plants have superb flowers that last for days or even weeks if given proper care. The long lasting qualities of many of these plants make them excellent choices for offices, public buildings, and homes. For more information on the proper temperature, watering, and lighting needed to encourage growth and development of plants in your home, consult the fact sheet entitled "Caring for Houseplants."
Deciding whether to keep a flowering houseplant after it finishes blooming depends on the species. Some flowering houseplants, such as Christmas cactus (Schlumbergera truncatus), bloom seasonally if placed in the conditions necessary to promote flowering. Others, referred to as flowering pot plants, are forced to flower specifically for a holiday and then are usually discarded. The effort necessary for a homeowner to get the plant to rebloom may be extensive. Such plants include Christmas pepper (Capsicum annuum) and Christmas begonia (Begonia cheimantha).
Plants that are easy to flower again
Most plants will grow better and give more satisfactory results if they can be planted outdoors during the summer. The outdoor environment more closely matches the plant's natural habitat than the interior environment where we place the plant most of the time. Select a lightly shaded area in the garden, protected from strong winds, where the containers can be plunged into the soil up to their rims. If possible, put stones or gravel in the bottom of the hole before sinking the containers--this will ensure good drainage. Twist the containers every two weeks to discourage roots from growing through the drainage hole and becoming established in the soil. Water the plants when needed and increase the frequency with which the plants are fertilized when they are actively growing. As soon as night temperatures begin to cool enough to where there is a threat of frost, bring the plants back inside. Plants, such as poinsettia (Euphorbia pulcherrima), must be brought in as soon as the night temperatures fall below 60°F. Otherwise the plant will suffer permanent damage.
Easter lilies (Lilium longiflorum)
will bloom as an outdoor plant or can be forced again indoors, though they are not as easy to force as other spring bulbs. While the plant is displayed indoors in a bright location away from direct sunlight, remove flowers from the plant as soon as they die. After the plant stops blooming it will require much less water. When the plant turns brown, cut it off at the soil line. For outdoor culture, plant it in the garden in May after the last spring frost. Plant the bulbs 4 to 6 inches deep in a sunny, warm location. After the ground freezes in the fall, mulch the area until you see new growth in the spring; then remove the mulch a little bit at a time.
For indoor culture, remove the bulb from the container after the plant has turned brown. Store it in a cool, moist place, such as a basement. Repot it in a 6-inch container in new potting mix a few weeks before Christmas. Then place it in a cool, sunny window until it blooms.
Azaleas (Rhododendron spp. and hybrids)
require large quantities of water when flowering and actively growing, hence, they may need to be watered every day during these periods. Mist leaves frequently to prevent them from shedding, and remove flowers as soon as they have faded. Keep your azalea in a bright location away from direct sunlight and pinch back new growth until it is warm enough for the plant to be placed outside, where it should remain until fall. At this time, place it in a cool location (as low as 45 to 50°F) with lighting, but reduce watering, until the buds start to swell. Cool temperatures are necessary for bud development, while light is necessary at this time to prevent leaf drop. When buds start to open, bring the plant into a bright, slightly warmer (60°) room. Continue to water moderately, but do not let the potting mix dry out during this time or the buds may drop.
Azaleas also require an acid potting mix and should be watered with rainwater to prevent the potting mix from becoming alkaline. Fertilize weekly with azalea specific fertilizer and when repotting an azalea, use an azalea or rhododendron potting mix.
Hydrangeas (H. macrophylla)
are similar to azaleas in that they also need a cold period in the fall to develop flower buds and should be well watered when actively growing, especially when flowering. Prune them back to about 3 inches in height just before you set them outdoors after the last frost date. To prevent the new growth from becoming unsightly, fertilize once a month with a general garden fertilizer, such as 5-10-5 or 5-10-10.
Leave the plant outside as long as possible in the fall and cover it at night to protect it from early light frosts. When frosts become more regular bring the plant into the basement or another very cool (40°F), dark place and leave it there until the first of January. Be careful to prevent the plant from freezing. The leaves will drop off during this period, so it will be necessary to keep them picked up to prevent any diseases from starting. About January 1, place the plant in bright light in a warmer room with a temperature between 55 and 60°F. It should now bloom for Easter.
Hydrangea blooms can be blue or pink, depending on the acidity of the potting mix. To get blue blooms, apply aluminum sulfate at the rate of ¾ of an ounce to ¼ of water. Apply this every two months after you prune the plant. Do not use a complete fertilizer after you start the forcing period (after January 1). The phosphorus in the fertilizer will make the aluminum unavailable to the plant.
To get pink blooms, add a teaspoon of limestone to the container in August; and during the forcing period (after January 1), water the plant with a solution of ¼ teaspoon of general garden fertilizer once every 10 days.
It may take several weeks or months for the color of your hydrangea to change. When the color change does occur, you may notice that the resulting color is not as you expected. This is because certain varieties develop better blue flowers than pink, and vice versa. It is not possible to change the color of white hydrangea varieties.
Christmas cactus and Thanksgiving cactus (Schlumbergera hybrids)
require cooler temperatures and need to be watered less frequently in the fall for buds to develop. Once flower buds have formed, temperature and watering regime should be increased. After the plant stops blooming, keep it in a cool, sunny location out of direct light. In summer, put it outside in light shade and leave it there as long as possible into the fall to promote new shoot. If you must bring the plant inside before outdoor temperatures decrease in the fall, leave it in a cool, light area in the basement. Place it in a bright location as soon as buds are noticeable. If buds start to drop, it may be an indication of one of three things:
- the plant may need repotting (refer to the fact sheet entitled "Repotting Houseplants" for more information);
- the light intensity may be too low; or
- the temperature may be too high. These plants seldom flower well at temperatures above 70°F.
Plants which are more difficult and challenging to flower again
Now we come to plants that are more challenging to flower again. These plants take a little bit of extra work to bloom satisfactorily another year creating a challenge and, therefore, some extra enjoyment when you are successful.
Poinsettia (Euphorbia pulcherrima)
is one of the most striking and popular holiday plants. Considerable care must be given if plants are to remain in top condition for extended periods of time. These plants are particularly sensitive to sudden changes in temperature, improper watering, and low light intensities. Place plants in a warm, sunny window, supply ample water to prevent the potting mix from drying out completely, and mist the leaves frequently. Temperatures below 55° or above 75°F have adverse effects on the poinsettia. Poinsettias also require an application of a complete soluble fertilizer to keep the plant in top condition.
After the plant is done flowering and its leaves have fallen, prune it back to 3 to 5 inches above the soil line. At this time store the plant in a cool (55 to 59°F), well ventilated place until May and water less frequently. However, do not let it dry out in storage. Repot the poinsettia, move it to a warmer location in the home, and increase the frequency of the watering. As soon as exterior night temperatures are above 60°F, move it outside into light shade. Pinch back each shoot once during the summer to get a well-shaped plant.
When night temperatures begin to cool in late August, bring your plant inside to a warm, sunny window. Day temperatures should be between 70 and 75°F and night temperatures should be no higher than 60 to 62°F. The plant should be fertilized every 7 to 10 days with a solution made by dissolving ½ teaspoon of a complete soluble fertilizer such as 15-15-15 in a quart of warm water.
Poinsettias form flower buds under conditions of long nights. If plants are to flower again for Christmas, they must be kept in an unlit room at night. The same effect can be achieved by covering plants with a light-tight box between 5 p.m. and 8 a.m. from the first of October until Thanksgiving. After this period flower buds will be well formed, and plants will suffer no adverse effect from light during this period.
Pot chrysanthemums (C. morifolium) are available from florists year-round and if properly cared for, can flower for six to eight weeks. They require full sun, temperatures between 60 and 70°F, and large quantities of water. Throughout their active growing season apply a solution of one-quarter teaspoon of general garden fertilizer to a quart of water every six weeks.
To encourage the pot chrysanthemum to reflower, cut off the spent flowers and keep the plant growing in the house until you can set it outdoors in the spring. Handle the plant in the garden the same as garden varieties, but pot it in September before the first frost. Keep the plant in full sun after it is placed in the house until October 1, when it should be given artificially short days like the poinsettia. The plant should bloom sometime between Thanksgiving and New Year's Day.
Kalanchoe (K. blossfeldiana)
needs to be placed in a sunny location in the home for flowering, which makes the plant difficult to flower a second year. It is better to place root cuttings in moist sand and carry them over. The parent plant usually gets quite spindly after several months in the poor light. Like poinsettia and chrysanthemum, kalanchoe is another photoperiod responder, and will need to be given the same "dark" period in order to promote flowering. It does not, however, need to be cut back in the spring.
Cyclamen (C. persicum)
is one of the most difficult winter pot plants to keep for more than a few weeks in a home. The key to a long-lasting plant is cool temperature. If the night temperature is much above 50°F, the leaves will turn yellow and the buds will die. If the light is also poor, the leaves will die quickly. Large amounts of indirect sunlight and cool temperatures are essential to the life of your cyclamen. Water the plant as soon as the potting mix is dry to the touch on top. Avoid getting any water into the crown of the plant by immersing the container in room temperature softened water until the top of the potting mix appears wet. Then remove the container, let it drain and return the cyclamen to its location. Given proper care, your cyclamen should bloom until March.
After the plant stops blooming, gradually reduce the amount of water and allow the plant to dry. Remove the corm from the potting mix and store it in sand, peat moss, or vermiculite to keep it from drying out. Store the corm in the basement at 50°F. In June repot it in a new potting mixture of one part peat moss, one part garden soil, and one part sand. Be certain to keep the upper half of the corm above the soil surface to help prevent rotting. Water the plant and in about three weeks, move it out to the garden to a shady place. Fertilize the cyclamen about twice a month with a solution of ¼ teaspoon general garden fertilizer, such as 5-10-5, to a quart of water. Before frost, bring the cyclamen back indoors to a cool, sunny window. The blooms will not be as large as the first year, but there should be as many.
Gardenia (G. Jasminoides)
is an attractive flowering and foliage plant and it grows best in a cool, sunny window. If the window is hot during the day, provide some shade. Nighttime temperature should be 60°F, while day temperatures should be 10° warmer. The key to an attractive gardenia plant in the home is high humidity. A gardenia grown in low humidity may form flower buds, but they will blacken and fall before opening. To maintain a high humidity, mist leaves daily or place the container over a tray containing pebbles and water. The bottom of the container should rest on the pebbles, which are above the water level.
Gardenias are similar to rhododendrons and azaleas and grow best when the potting mix is mildly acidic. To achieve this, incorporate large quantities of peat moss into the potting mix. You should use fertilizers especially designed for acid loving plants. If the leaves become yellow and drop, the potting mix may not be acidic enough, the humidity or temperature may be too low, or the plant may need repotting (refer to the fact sheet entitled "Repotting Houseplants" for more information).
In summer, move the gardenia outdoors to a lightly shaded area. Never let the potting mix dry out so that the plant wilts. Maintain the regular fertilizer schedule and bring the plant back indoors before heating is needed in the fall.
Plants to be discarded after they flower
A large number of beautiful plants that should be kept for only one blooming season are available during the holidays. They are either annuals or they cannot adapt to growing conditions in the home. Since this is true, it is essential that these plants last as long as possible after they are placed in the home.
Jerusalem cherry (Solanum pseudocapsicum) and Christmas pepper (Capsicum annuum) are purchased when the fruit is ripe. Therefore it is natural that they will begin to drop quickly. To make them last as long as possible, keep them in a night temperature of 55°F and place them in full sun during the day. Do not let the potting mix dry out. Misting the leaves and fruit every morning can further prevent fruit drop.
Primrose (Primula spp.), calceolaria (C. herbeohybrida), and cineraria (Senecio cruentus) all tolerate the same conditions in the home. Purchase plants that have both open flowers and buds. To get full color in the buds as they develop, the plant must be in full sun and have plenty of water. A cool temperature of 50°F at night is also preferable. Keep the faded flowers picked off. Since these plants are annuals, they should be discarded after blooming.
Christmas begonia (B. cheimantha) will last for several months if it is purchased with a large number of buds. As with most of the flowering plants, the best location for it in the home is a cool, sunny window, avoiding temperatures above 70°F. If you let the plant become dry, the life of the flowers will be greatly shortened. This plant is almost impossible to grow in the home; therefore, it should be treated as an annual and discarded when it is through blooming.
Suggested Further Reading
- Hessayon, D.G. 2002. The Houseplant Expert. Transworld Publishers, London.
- Jantra, I. and Kruger. 2000. The Houseplant Encyclopedia. Firefly Books, New York.
- Kramer, J. 1999. Easy-care Guide to Houseplants. Creative Homeowner, Upper Saddle River, New Jersey.
Prepared by William R. Fortney, retired associate professor of horticulture. Reviewed and Revised by Kathleen M. Kelley, assistant professor of consumer horticulture and Mary Concklin, Montgomery County horticultural extension educator.