Amaryllis like moist, but not soggy soil. Don't let the bulb dry out especially once it starts to flower. Rotate the pot daily as it grows so the plant doesn't lean to one side. Ideal temperature is 55-65°F. Warm temperatures promote weak and spindly growth.
The longer you have an amaryllis bulb, the bigger the bulb will grow. The larger the bulb, the more flowers so it is worth the little effort to keep it year after year.
After your Amaryllis has bloomed, remove the flower stalks but leave the leaves. Fertilize it regularly with a general houseplant food. Grow the Amaryllis in a bright window until all danger of frost is gone, then it can be placed outdoors in the shade. (Keep it in its pot).
In order to get an Amaryllis to bloom again it must go into a rest period.
Around five to six months after the first flower stop fertilizing and gradually reduce watering over a three week period, then stop. This is usually around the middle of August. Let the plant die back naturally, cutting the leaves as they turn yellow about three inches above the bulb. In September, place the Amaryllis in a cool dark place (50 -60 degrees) for six to eight weeks. This time shouldn't start until all the leaves are yellow and cut back. In mid-November, the growth cycle needs to start again. Move the Amaryllis back into a warm bright area and begin watering and fertilizing. In four to six weeks you should have a beautiful flowering Amaryllis again.