Plant an Amaryllis bulb in a pot one or two inches larger in diameter than the bulb. Make sure the pot has drainage holes. Repot old bulbs in fresh potting soil each year. Plant a bulb so that 1/3 of the bulb (the nose) is exposed. Water the bulb thoroughly after planting and put it in a bright, cool room. Water only when the soil is dry. Too much moisture can cause the bulb to rot. As the roots begin to develop and fill the container, the soil will dry out more quickly.
Keep amaryllis away from cold drafts and hot spots. Once top growth begins, move the pot to a sunny window. Rotate the plant every day or two to prevent the stem from leaning toward the light. If the plant gets top heavy, tie the stem to a bamboo stake.
Flowers should appear in 7-10 weeks. To extend the flowering time, remove the long pollen-bearing stamens inside the flower with tweezers, and keep the plant in a cool spot. Once the flowers are finished, cut the flower stalk off with a sharp knife one inch above the bulb. Do not remove the leaves.
After cutting off the flower stalk, keep the amaryllis in a bright location and keep the soil moist. Treat it like any other houseplant, fertilizing and watering regularly. The goal is to keep the plant growing so it can store energy for the next year's flowers.
In early August, stop watering the plant and allow the leaves to dry off naturally. This starts a resting or dormant stage that the bulb needs in order to flower again. When the leaves have withered, remove the bulb from the pot, brush off the soil, and keep it in cool, dark storage. Then repeat the process, replanting the bulb 7-10 weeks before Christmas.