Department of Horticultural Science
Part 1 -- General Aspects
The Amaryllis (Hippeastrum) is a true bulb that originated in the tropical areas of South America. Thus, it is a tender bulb. It performs best when grown under warm (70 to 75 oF) temperatures for 9 to 10 months to promote flowering and vegetative growth, followed by 2 to 3 months of either cool (55 oF) dry storage or cool (55 oF) growing conditions. The use of one of the latter conditions is required to promote reflowering of the bulb.
Most marketed bulbs sold are greater than 8 inches (20 cm) in circumference, and are either Dutch, Israeli, or South African-grown. They produce 2 to 6 flowers per floral stalk, with the average being 4. Very large bulbs normally produce 2 flower stalks. Flower colors are red, white, pink, orange, salmon, and bicolored (mostly whites with pink or red flushes). Plant heights range from 18 to 36 inches depending on the cultivar, the country in which the bulb was produced, and home forcing conditions.
Part 2--Indoor Growing of New or Replanted Bulbs
Planting --Plant in a well-drained, pH 6 to 6.5, sterilized potting medium. Do not use a medium that contains pine bark! An equal mixture of peat and perlite is excellent. Use a standard-depth (6-inch diameter) pot that has adequate drainage holes. Carefully plant the bulb, with 1/3 being above the rim of the pot.
Watering -- After planting, thoroughly wet the medium with lukewarm water. Then keep it moist, but not wet. Don't over-water! Initially, once per week is usually adequate. Avoid watering over the bulb nose.
Temperatures -- Initially grow at 70 to 75 oF until bulb begins to root and the leaves and floral stalk(s) begin to grow. Afterwards, any temperature from 65 to 75 oF can be used. When in flower, the coolest area in the home is best.
Light -- In the home, the plant should be kept in a well-lighted area. A southern exposure is best. When plant is flowering, keep it out of direct sunlight. This helps to promote a longer flower life.
Fertilization -- After the plant begins to grow, fertilization is essential. Use either a complete nitrogen, phosphorous, potassium (NPK) slow- release fertilizer that lasts several months or a liquid (NPK) fertilizer, 2 to 4 times per month.
Flower Removal -- As the flowers fade, carefully cut them off.
Flowering Stalk Removal -- After all flowers fade, carefully cut the floral stalk off just above the bulb nose. Take care that the water that normally runs out of the freshly cut stalk does not run onto furniture, etc.
Part 3 -- Outdoor Growing Conditions
Amaryllis (Hippeastrum) can be grown outside in Climatic Zones 8 to 10. In other climatic zones, the plants can be placed outside after the danger of frost has passed. Plunge the entire pot in the garden bed and fertilize the bulb 2 to 3 times per month. Avoid placing the bulb where it will dry out excessively. In cooler climatic zones, the plants must be brought indoors in September.
Part 4 -- Reflowering of the Bulb
If the bulb has retained its original bulb size or if it has gained in size, it can be reflowered. The key is to place the bulb at a temperature of 55 oF for a minimum of 8 to 10 weeks. This can be accomplished either by withholding water and then placing the bulb in a cool storage area or, preferably, by placing the plant in a cool (55 oF) growing location for this length of time. It is not necessary for the plant to go dormant! Once the plant has received 8 to 10 weeks of 55 F, follow the growing instructions described in Part 2 of this leaflet.
Part 5 -- Dividing Older Bulbs
If the bulbs have been grown for 2 or more years, most cultivars will produce offset (daughter) bulblets. Homeowners can handle these bulbs in one of two ways. First, the bulbs can be transferred to a larger pot with the bulblets left attached. By doing this, a large number of flowering bulbs will ultimately be growing in a single pot. This creates quite a show. Alternatively, the bulblets can be carefully removed from the mother bulb and each of them planted in individual pots. Normally, this takes place after the bulbs have been stored dry for 8 to 10 weeks as described in Part 4 of this leaflet.
Part 6 -- Diseases and Insects
Normally, when healthy bulbs are purchased, few diseases or insects are encountered. The major potential disease is Stagonospora (Fire or Red Spot). The insects that can become a problem are: mites, thrips, and mealybugs. If any of these pests are encountered, contact your local Cooperative Extension office for advice on pesticides available for use on them.
De Hertogh, A. A. 1996. Holland Bulb Forcer's Guide, 5th ed. International Flower Bulb Centre, Hillegom, The Netherlands.
Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.