Knight's Star Lily Hippeastrum

Amaryllis are ornamental herbaceous perennial bulbs in the Amaryllidaceae family. They are native to Central America and South America and grow 1 to 3 feet tall and up to 1 foot wide. There are over 100 species and hundreds of cultivars. The flowers range in colors of red, pink, white, orange, salmon, and bicolor, and they may produce two to six flowers per stalk. There are single or double flowering, and miniature varieties available. 

The genus name, Hippeastrum, originated from the Greek words hippos which means horse, and hippeus meaning rider. It was thought that the flower appeared to look like the head of a horse. The common name, Amaryllis, can lead to some confusion because there is a genus also called Amaryllis that is native to South Africa. 

Amaryllis grow best in full sun or partial shade and in soil high in organic matter and moist but with good drainage. They tolerate drought but need moisture during the active growing season. When planting, bury only half the bulb below the surface with the narrow part of the bulb (the “neck”) well above the soil line. Bulbs may be started indoors in early spring and moved outside for late spring to early summer bloom. Propagate amaryllis by division or seeds. Note that plants are injured at temperatures below 35 degrees F. They can, however, survive the winter outdoors in zones 7 and 8 if properly mulched. In zones below 7, amaryllis bulbs are grown as houseplants for a pop of color during the winter holidays. Pot them between mid-autumn and late winter for bloom approximately five weeks later.  

Amaryllis bulbs need a dormant period of recovery and rejuvenation after bloom. Remove flower stalks but leave the foliage intact to wither on its own. Reduce watering. When the foliage turns brown, remove it. If the plants are being grown outdoors, add a layer of mulch 2 or 3 inches deep. If the plants are being grown indoors, move them to a cool (50 to 55 degrees F), semi-dark location to rest. Let them be dormant for 8 to 10 weeks. To restart the growth cycle, move plants to a well-lit, warm (70 to 75 degrees F) location and resume watering. 

The large, showy blooms of amaryllis last for three to four weeks making them great for use in borders, cutting gardens, as specimens or garden accents, and as houseplants. Amaryllis are very popular as indoor flowering bulbs during the winter months.  

Quick ID Hints:

• bulbs produce one or more 12 to 24-inch tall, erect, hollow, stout leafless flower stems
• large strap-shaped, smooth, glossy green leaves
• 2 to 6 large showy flowers in an umbel inflorescence that bloom at the top of the scape
• 2 bracts enclose the flower buds until they bloom
• each trumpet-shaped flower has 6 colored tepals (3 petals and 3 sepals)
• 6 bundled stamens and filiform style with a trifid stigma
• fertilized flowers produce a capsule that is filled with flat brown or black seeds

Diseases, Insects, and Other Plant Problems: Mealybugs are occasional visitors. Watch for snails and slugs if plants are outdoors.

Please note that the common name Amaryllis is applied both to Hippeastrum species, which are the commonly cultivated bulbs discussed here, and to the genus Amaryllis, which is less commonly cultivated (and comprises only two species native to South Africa).  

VIDEO Created by Elisabeth Meyer for "Houseplants, Succulents, and Cacti" a plant identification course offered in partnership with Longwood Gardens.