After an amaryllis flowers, the stalk should be cut back and the plant kept moist until the leaves start to go yellow. Amaryllis bulbs need to go dormant for summer and benefit from being stored somewhere cool and not being watered.
Either keep them in a cool spot in the home or place your amaryllis in a sheltered spot outside, away from strong sunlight. After a couple of months, they can be top-dressed with compost and placed back in a sunny spot.
Resume watering and feeding and the plant can start to grow again. It is better to keep the amaryllis bulb in the pot for as long as possible, rather than lift the bulb annually, as the plants do not enjoy root disturbance.