Although amaryllis can be grown as garden plants in some warmer areas of the country, they are most often used as an indoor plant to brighten the winter months. While many indoor growers discard their bulbs after the first year, there are ways to keep the bulbs growing over the summer months for a repeat performance the next year.
Amaryllis come in many varieties including white, pink, red or striped, double or single flowering and even dwarf varieties. It is important when choosing a plant for holiday bloom that the bulb that has been pre-chilled or conditioned. Purchasing from a reputable grower is also important as is the bulb's size. Most growers will note how large their bulbs are in inches and if their bulbs are "top-size," which should indicate a large, solid bulb. Many prepackaged kits contain smaller bulbs which may not bloom as well.
When planting amaryllis for indoor growth, the bulb should only be covered with soil by half. This helps prevent the plant from producing only foliage. A well-balanced fertiliser should be used. Too much nitrogen, either from a nitrogen rich soil or too much fertiliser, will deter flowering. Most amaryllis will begin to produce the flower stalk, followed by several leaves, before beginning to bloom. Amaryllis also require bright light in order to flower.
Many growers discard their amaryllis bulbs after the first year of growth. However, they can be encouraged to re-bloom by giving them a resting period. After the bulb flowers, cut back the stalk but retain the leaves. Keep the bulb watered and fertilised throughout the summer. Approximately 10 to 12 weeks prior to the desired bloom time, discontinue watering and store the plant in a cool area (about 12.8 degrees C). It will be normal for the leaves to yellow and wither. They should then be cut back to about 1 inch from the bulb. When new growth begins, move the plant to a warm, brightly light location and treat it in the same growing manner as its first season. If the plant is not allowed to rest in this way, it may begin to grow again but will most likely only produce leaves and no flower stalk.
If you allow your amaryllis to summer outdoors, be sure to wipe the leaves with a soft, damp cloth before bringing it in and check the soil for pests. Spider mites and aphids are a few common pests on indoor amaryllis and they should be checked for periodically.
Amaryllis are native to South America and have been known to live up to 75 years. Most amaryllis available for indoor forcing are hybrids of these native plants.