Yard And Garden: Keeping Your Holiday Plants Blooming

By Richard Jauron, Greg Wallace

Everyone loves holiday flowers – they’re beautiful and a perfect addition to holiday celebrations. But they aren’t much good if they don’t bloom, are they? In order to make holiday flowers perennial and beautiful for years to come, special care must be taken. Horticulturists with Iowa State University Extension and Outreach tell how to make sure holiday plants look great for years to come. To have additional houseplant questions answered visit the Yard and Garden FAQs, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.

Why doesn’t my Christmas cactus bloom? 

The Christmas cactus requires proper environmental conditions to flower. Critical factors in flower initiation are day length and temperature. The Christmas cactus is a short-day plant.  Short-day plants grow vegetatively during the long days of summer and produce flowers when days become shorter in fall. The Christmas cactus will not bloom properly if exposed to artificial light at night in fall. Flowers may also fail to develop if the plant is exposed to temperatures above 70 degrees Fahrenheit.

Night temperatures of 60 to 65 degrees Fahrenheit with slightly warmer daytime temperatures are ideal for flower formation. In late summer, place the Christmas cactus in a cool location that receives bright light during the day, but no artificial light at night.  An unused bedroom or basement may have the proper environmental conditions. To avoid flower bud drop, do not move the plant during flower bud development. The Christmas cactus can be moved and displayed in another room when the first flowers begin to open.

An amaryllis bulb saved from a previous year produces leaves, but doesn’t bloom. Why?

An amaryllis bulb purchased at a garden center or other retail business typically blooms six to eight weeks after the bulb is potted up. In succeeding years, proper cultural practices must be followed to get the bulb to bloom on an annual basis.

After the amaryllis bulb has been potted up and flowered, cut off the flower stalk with a sharp knife. Make the cut one to two inches above the bulb. Don’t damage the foliage. In order for the bulb to bloom again next season, the plant must replenish its depleted food reserves. The strap-like leaves manufacture food for the plant. Place the plant in a sunny window and water when the soil surface is nearly dry. Fertilize every two to four weeks with a dilute fertilizer solution.

The amaryllis can be moved outdoors in late May. Harden or acclimate the plant to the outdoors by initially placing it in a shady, protected area. After two to three days, gradually expose the amaryllis to longer periods of direct sun. The amaryllis should be properly hardened in seven to 10 days. Once hardened, select a site in partial to full sun. Dig a hole and set the pot into the ground. Outdoors, continue to water the plant during dry weather. Also, continue to fertilize the amaryllis once or twice a month through July. Bring the plant indoors in mid-September. Plants left indoors should be kept in a sunny window.

In order to bloom, amaryllis bulbs must be exposed to temperatures of 50 to 55 degrees Fahrenheit for a minimum of eight to 10 weeks. This can be accomplished by inducing the plant to go dormant and then storing the dormant bulb at a temperature of 50 to 55 degrees Fahrenheit. To induce dormancy, place the plant in cool, semi-dark location in late September and withhold water. Cut off the foliage when the leaves turn brown. Then place the dormant bulb in a 50 to 55 degree Fahrenheit location for at least eight to 10 weeks. After the cool requirement has been met, start the growth cycle again by watering the bulb and placing it in a well-lit, 70 to 75 degree Fahrenheit location.

Keep the potting soil moist, but not wet, until growth appears. The other option is to place the plant in a well-lit, 50 to 55 degree Fahrenheit location in fall. Maintain the amaryllis as a green plant from fall to early to mid-winter. After the cool requirement has been met, move the plant to a warmer (70 to 75 degree Fahrenheit) location.