By Carl Wilson, Colorado State University Cooperative Extension agent, horticulture, Denver County
Anyone who has seen the massive size of a six-pointed amaryllis bloom will not soon forget it. The 8-to-10-inch blooms can be yours to enjoy by the Holidays if you start your bulb between Nov 1 and 15.
Botanically called Hippeastrum, meaning "horse star," an amaryllis is easy to grow. Its bulbs are nearly the size of grapefruit and the larger the bulbs, the larger the flowers. Bulbs are sold pre-planted in starter kits. They come in a loose planting mix in pots only slightly larger than the bulb itself. The bulb is positioned halfway out of the soil.
To start, water thoroughly, allow to drain and don't water again until growth begins. The first sign of growth will be the flower bud itself as the foliage won't develop until the flowers are opening.
Once bud growth is visible, put plants on a routine. Keep soil moist, provide at least half day of bright light, and fertilize once a month. Stems grow rapidly to 12-24 inches and will produce a sequence of blooms that last about a month.
Amaryllis are a long-term investment. With a little year-round care, they will produce mid-to-late winter blooms for years. After flowering, water the plant as a houseplant for the remainder of the winter. Set plants outside after all danger of frost is past; you can bury pots in a partially shaded location. Lift pots in early September, bring indoors and gradually cut back water. To ripen foliage, plants should receive no water from october 1 until it is time to re-trigger growth.
Cut foliage once it has dried and let the bulb rest for at least a month before starting the bloom cycle. Trigger growth by washing an inch or two of the old surface soil away, then replenish with fresh soil and water. Bulbs need complete repotting after three or four years.
Amaryllis won't replace poinsettias as the Christmas plant but they do make a spectacular holiday decoration. Two of the best standard red varieties are "Fire Dance" and "Scarlet Admiral," and a good white is "White Giant." Look for newer improved varieties from Holland that include "Oscar," a sculptured dark red; "Vlammenspel," a red with white stripes; "Clown," a white finely striped with red; and "Christmas Gift," a new white. Or, try a miniature called "Scarlet Baby" that has smaller blooms, but more of them.
Bulbs identified only by color are seed propagated and likely won't produce the superior flowers of the bulbs or potted plants sold under a variety name.
If you buy plants or start bulbs for bloom later in the winter, you may want to try other colors that include pink, orange, peach, wine red and salmon.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010