Amaryllis (Hippeastrum)
The familiar pot-grown holiday amaryllis can be planted in the garden where they are impressive when grown in clumps of 10 plants or more of the same color. Use them as a foundation planting against nearby evergreen shrubbery. Amaryllis can survive the winter outdoors in zones 7 and 8 if mulched 2- or 3-in. deep. (Plants are injured at temperatures below 35 degrees F.)
To plant holiday plants in the garden, remove the flower stalks after the flowers have died and before seed pods are produced. If not, flowering the following season may be greatly reduced. Allow the leaves to die back naturally.
When planting, bury only half the bulb below the surface with the narrow part of the bulb (the “neck”) well above the soil line, similar to how they grow when properly planted for growing in a pot indoors.
Amaryllis are sun-and shade-tolerant, but they do best in light shade such as under pine trees. They grow best in soil high in organic matter and moist but with good drainage. If the site does not drain properly, create a raised bed to provide improved drainage. Once established they tolerate drought but need moisture during the active growing season.
Though tolerant of neglect, amaryllis benefit from at least one fertilizer application in early spring when they emerge. During the growing season (March through September), two or three light applications of a balanced (10-10-10 or similar) slow-release fertilizer with micronutrients are recommended.
Failure to flower can be caused by not allowing leaves to die back naturally, overcrowded bulbs, too much shade (which reduces the plant's ability to manufacture food and results in loss of vigor), soil that is too rich / too much fertilizer, or too much water -- any of which can cause amaryllis to produce leaves at the expense of bulb growth and flowers).
The bulbs may be left in the ground for years without being dug, separated, and replanted each year. However, if bulbs are crowded, dividing them will encourage uniform flowering and larger blooms. Digging also provides an opportunity to discard unhealthy bulbs, remove young offsets (bulblets), and amend the bed with organic matter.
Amaryllis are resistant to deer and rabbits. Mealybugs are occasional visitors. Watch for snails and slugs if plants are outdoors. Occasionally, amaryllis will be attacked by a fungus disease called "red blotch" or "leaf scorch" (Stagonospora curtisii). It usually occurs on shaded plants that are frequently irrigated. Occasional chewing insects, such as caterpillars, may be encountered.
'Voodoo' Flowers - May - Wake Co., NC Cathy DeWitt CC BY 4.0
NOTES: (1) The common name amaryllis can lead to some confusion because it is applied both to Hippeastrum species, discussed here, and to the genus Amaryllis, which is less commonly cultivated and comprises only two species native to South Africa. (2) This plant has medium severity poison characteristics.
Hippeastrum 'Vera,' Amaryllis Cindy Christian CC BY 4.0
By Kathryn Copley, Extension Master Gardener SM Volunteer, Brunswick County, NC
For more information on gardening in Brunswick County, please call the Brunswick County Cooperative Extension Office, 910.253.2610.
SOURCES:
Hippeastrum (Amaryllis, Dutch Amaryllis, Fire Lily, Knight's Star Lily) | North Carolina Extension Gardener Plant Toolbox
Amaryllis | Ask IFAS, University of Florida