November 3, 2011

Yard and Garden: Blooms at Christmas

By Richard Jauron
Iowa State University Extension Scott County

Several popular potted plants will bloom, if cared for properly, during the Christmas season. Iowa State University Extension horticulturists explain the steps to take from early October through November to ensure blooms in December. To have additional houseplant questions answered, contact the ISU Extension Hortline at 515-294-3108 or

When should I plant an amaryllis bulb to have it in bloom at Christmas?

An amaryllis bulb usually blooms about six weeks after planting. Plant the amaryllis bulb in early to mid-November for spectacular blooms at Christmas. To increase your odds of having an amaryllis in bloom at Christmas, pot up one amaryllis bulb in early November and a second one several days later.

How do I get a poinsettia to bloom for Christmas?

Poinsettias are short-day plants. Short-day plants grow vegetatively during the long days of summer and produce flowers when days become shorter in fall. In order for poinsettias to flower for Christmas, they must receive complete darkness from 5 p.m. to 8 a.m. each day from early October until the bracts show good color, usually around early December. (Most poinsettia varieties require eight to 10 weeks of short days to flower.) Gardeners can protect their plants from light by placing them in a closet or by covering with a cardboard box. When using cardboard boxes, cover any openings to insure complete darkness. Exposure to any kind of light between 5 p.m. and 8 a.m. will delay or possibly prevent flowering. During the remainder of the day, the poinsettias should be placed in a sunny south window. Keep the plants well watered and fertilize every two weeks with a dilute fertilizer solution during the forcing period. While poinsettias are difficult to flower in homes, proper care can reward home gardeners with a colorful plant for the holiday season.

How do I care for my Christmas cactus in fall?

Day-length and temperature control the flowering of the Christmas cactus. The Christmas cactus is a short-day plant. Plants will not bloom properly if exposed to artificial light at night. Flowers may also fail to develop if the plant is exposed to temperatures above 70 degrees Fahrenheit. Night temperatures of 60 to 65 degrees F with slightly warmer daytime temperatures are ideal for flower formation. In early fall, 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. Keep the Christmas cactus a bit on the dry side in fall. A thorough
watering every 7 to 10 days is usually sufficient. Continue to give the Christmas cactus good, consistent care during flower bud development. Moving the plant from one location to another, excessive watering or other changes to its care during flower bud development may cause the buds to drop off. The Christmas cactus can be moved and displayed in another room when the first flowers begin to open.