Amaryllis (Hippeastrum) are perennial bulbs known for their large, showy flowers. They are most often sold in the fall for forcing to bloom indoors in late fall and winter, especially in time for the holidays. The trumpet-shaped flowers are available in various colors, including red, white, pink, orange, salmon, yellow, and green, with color patterns including bicolor, striped, etc. Flowers can be single or double and are 5 inches wide by 6 inches long.
Each amaryllis bulb produces tall flower stalks that grow from one to three feet tall. The larger the bulb, the larger the flowers, and the more flower stalks that are produced. Amaryllis bulbs are sold according to the diameter of the bulb and are usually labeled in centimeters. Generally, a bulb 30 to 32 centimeters (11.8 to 12.5 inches) in circumference will produce two flower stalks with 3 to 4 flowers per stem. Larger bulbs will be a year older and produce up to three stalks with 4 to 5 blooms per stem. Most amaryllis bulbs purchased in the United States in the fall have been grown in the Netherlands (sold as Dutch amaryllis) or South Africa. However, amaryllis are not native to those regions. They are native to South and Central America and the Caribbean.
There are over 90 species and hundreds of hybrids of amaryllis available today. In addition to the large-flowered hybrids sold in the fall, many exotic types are available from catalogs and online sources. Cybister amaryllis (Hippeastrum cybister) has unique spider-like flowers and evergreen foliage. Trumpet amaryllis has long trumpet-shaped blooms like an Easter lily. Butterfly amaryllis (Hippeastrum papilio) hybrids typically have maroon stripes on cream petals and green throats. Miniature amaryllis have more flowers than the hybrids, and the individual flowers are smaller.
Growing Amaryllis Indoors
Amaryllis are most often grown indoors for flowers during the winter holidays. Flowers can be expected in 4 to 8 weeks when planted in early to mid-November. There are several methods for growing amaryllis indoors. The most common method is to plant the bulbs in a pot. Forcing the bulbs to bloom in water is another method. In recent years, waxed amaryllis that require no care have become popular.
Soil Mix & Container: Plant the bulb in a container that is one to two inches larger in diameter than the widest part of the bulb. Potted bulbs thrive under conditions in which they are slightly rootbound. Containers can be clay, ceramic, or resin and must have drainage holes in the bottom. Heavier pots are less likely to tip over once the tall flower stalks and blooms appear. When planting multiple bulbs in one pot, select a heavy pot with a broad base to counterbalance the weight of the blooms.
Plant amaryllis with about one-third to one-half of the bulb above the growing medium surface. Doing so keeps the bulb’s nose dry, which helps reduce red blotch infection, a fungal disease.
Plant in a well-drained, high-quality potting medium. A mixture containing equal parts peat and perlite is excellent.
Light & Temperature: The sun-loving amaryllis grows best indoors in a well-lighted area that receives at least four hours of direct sunlight daily. A southern window exposure is best, while an eastern- or western-facing window is second best. Rotate the pot every few days so the flower stalk will remain vertical and not lean toward the sun.
Amaryllis prefers warm temperatures (70 to 75 °F) for best growth until the roots form and the leaves and flower stalk begin to grow. Once the plant flowers, cooler temperatures (65 °F) will prolong the flower’s life. Do not place the blooming plant near a heater or air vent.
Water: Immediately after planting, thoroughly water the bulb and allow the water to drain. Do not let the pot sit in water in a saucer. Wait one week to water again. After that, keep the soil slightly moist and empty any saucer underneath the pot. When flowering starts, increase the watering frequency to one to two times per week. Watering the plant when the soil surface feels dry to the touch is best.
Fertilizer: Fertilizing an amaryllis bulb with no leaves can kill the roots, but after the plant grows, fertilization is essential. Fertilize amaryllis twice a month using a liquid houseplant fertilizer that is diluted in water according to the label directions.
Staking: Amaryllis can produce heavy flowers that cause the flower stalk to bend. Staking the flower stalk will help support the flowers. Should the flower stalk bend too far over, cut it and place it in a vase. The flowers will continue to bloom.
Care After Flowering: The secret of successfully growing amaryllis is to keep the plants growing after they bloom. Remove the blossoms as soon as they fade to prevent seed formation by cutting the stem off just above the bulb. Place the plant in a sunny window. Growth is active for several months and should be encouraged for future bulb development.
Keep the soil slightly moist and fertilize with a balanced houseplant fertilizer regularly. Amaryllis can be grown indoors all year or outdoors as soon as the danger of frost has passed in the spring.
Reflowering of the Bulb: Stop watering and fertilizing it for 8 to 10 weeks. The leaves will yellow and wither. When the top of the flower bud begins to emerge, put the pot in a sunny area and start watering it again. Remove all dry foliage. As the flower stalk begins to lengthen, rotate the plant every few days to prevent the stem from leaning toward the light.
Forcing Amaryllis in Water
Amaryllis can be grown in water in a vase, bulb-forcing jar, hurricane, or other clear container. The vase must be clear to monitor the water level as the plant grows. After flowering in water, these bulbs can be disposed of or potted in soil. They will not bloom again in water.
One method of growing Amaryllis in water is to use a bulb vase or forcing jar. These vases are transparent glass with a wide top for the bulb and a narrow neck or midsection that holds the bulb higher than the water in the bottom of the vase.
Add water to the bulb vase until it reaches one inch below the midsection of the vase. Place the bulb in the wide top, directing any roots down toward the water. As the amaryllis grows, it becomes top-heavy. To counterbalance the weight of the top growth, pebbles, marbles, etc., may be added to the vase for stability. Be sure to rotate the vase regularly so the stem will grow straight. Monitor the water level and refill as needed.
Another method of growing amaryllis in water is to use a large clear glass container, like a hurricane vase, with rocks so that the bulb is above the water level. Place pebbles, flat marbles, river rocks, shells, tumbled stones, or other vase fillers in the bottom of the container to a depth of 3 inches. Place the bulb on top of those pebbles, and then add more pebbles to the sides of the bulb. Leave the top 1/3 of the bulb visible. Add water to 1 inch below the bulb. Refill the water as needed.
Amaryllis bulbs dipped in colorful wax are available online, in catalogs, and in retail stores during the holiday season. These bulbs do not require water or soil because they contain enough stored energy to flower for the season. They do need light and warmth to bloom. Expect two flowering stalks per bulb. As the flower stalk grows, rotate the bulb daily to help the stalks grow straight.
Often, the wax is poured so that the bottom of the amaryllis bulb sits flat, ensuring it stands upright. A coiled wire may also be in the bottom of the bulb to hold it upright.
Waxed amaryllis are intended to be discarded after blooming.
For more information on bulbs, see HGIC 1556 Forcing Bulbs Indoors.
Growing Amaryllis Outdoors
Amaryllis makes an excellent landscape plant and is cold hardy in South Carolina through USDA planting Zone 8. Amaryllis grown indoors during the holiday season can be moved outdoors in the spring after the threat of frost has passed. Gradually acclimate the indoor plants to brighter light by moving them to a porch or patio area before planting them in the garden.
Amaryllis grow well in good garden soil if the site is well-drained. An elevated planting bed may be necessary to ensure good drainage. A soil rich in organic matter will provide the best growth. Plant bulbs directly into the ground, spaced about a foot apart. Plant the bulb with only half its nose above ground, leaving the tops barely covered with soil.
Select a sunny spot in the garden that receives shade during the afternoon. Avoid placing the bulb where it will dry out excessively. Apply mulch, especially during the fall and winter months.
Fertilization determines the size and quality of the flowers and foliage. For garden plantings, use fertilizers containing low nitrogen, such as 5-10-10 or 6-12-12 analysis. Apply 1 to 1½ pounds per 100 square feet or 100 feet of row to be established. A bulb booster-type fertilizer can also be used. Make the first fertilizer application as new growth begins, then repeat the application when the flower stalk is 6 to 8 inches tall. Apply a third application immediately after flowering when the old flower heads and stems have been removed.
Amaryllis grown outdoors are deer resistant.
The main disease problems of amaryllis are mosaic virus, bulb rots, and “red blotch.” Plants infected with mosaic virus have a light-yellow streaking of the leaves and reduced growth and flowering over the years. There is nothing one can do to eliminate the mosaic virus from an infected plant.
Bulb and root rot problems typically occur when the soil is kept too wet or when bruised bulbs are planted. When bulb or root rot problems are suspected, discard diseased bulbs and replace the potting soil.
The fungal disease “red blotch” or “leaf scorch” causes reddish brown spots on the bulb, leaves, and/or scape (flower stalk). It can spread rapidly within a bulb and from bulb to bulb.
Insects and other pests that can become a problem include scale, mites, thrips, bulb maggots, and mealybugs. For more information on controlling insect pests, see HGIC 2770, Less Toxic Insecticides.
All parts of the amaryllis are poisonous to humans and pets if ingested in large quantities. The bulb is the most toxic part of the plant.
Originally published 06/99