AMES — Amaryllis and holiday cacti provide lovely indoor blooms during winter months with proper care and planning. Iowa State University Extension and Outreach horticulturists offer tips for maintaining plants so they can be enjoyed for many years. To have additional questions answered, contact the Hortline at 515-294-3108 or at firstname.lastname@example.org.
My Christmas cactus doesn’t bloom well. Why?
Day-length and temperature control the flowering of Thanksgiving and Christmas cacti. (Thanksgiving and Christmas cacti are similar in appearance. Thanksgiving cacti bear two to four upward-pointing teeth on their stem segments and typically bloom from mid-November to late December, while Christmas cacti have stem segments with scalloped edges and bloom from late November to early February.)
Thanksgiving and Christmas cacti are short-day plants. Plants will not bloom properly if exposed to artificial light at night in fall. Flowers may also fail to develop if the plant is kept at temperatures above 70 degrees Fahrenheit. Night temperatures of 60-65 F with slightly warmer daytime temperatures are ideal for flower formation.
In September, place plants 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 Thanksgiving and Christmas cacti a bit on the dry side in fall. A thorough watering every seven to 10 days is usually sufficient. Continue to give plants good, consistent care during flower bud development. Moving plants to another location, excessive watering or other changes to their care during flower bud development may cause the buds to drop off.
Thanksgiving and Christmas cacti can be moved and displayed in another room when the first flower buds begin to open.
An amaryllis bulb saved from the previous year produced leaves, but didn’t bloom. Why?
An amaryllis bulb purchased at a garden center or other retail business typically blooms four to six 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 flowered, cut off the flower stalk with a sharp knife. Make the cut 1 to 2 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 50-55 degrees 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 50-55 F. To induce dormancy, place the plant in a 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 50-55 F 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, 70-75 degrees location. Keep the potting soil moist, but not wet, until growth appears. The other option is to place the plant in a well-lit, 50-55 degrees 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 (70-75 degrees) location.