1. Remove the dead flowers as they fade and cut the stalks to within 1 inch of the top of the bulb.
2. With the bulb still in the pot, continue to keep it in the sun with water and fertilizer.
3. The bulb will send out long, loping strappy leaves during this period.  These leaves photosynthesize and help to nourish the bulb as it rests for about 2-3 months. (late spring thru summer).  It does not need to rest in a dark place at this point.  I put my bulbs, still in their pots, outside under a tree for the summer.  Be sure your pot has drainage holes in the bottom to let the rain drain thru otherwise the bulb will rot.
4. In late summer, bring the Amaryllis bulb inside the house and place it in a sunny spot.  Stop ALL watering and feeding.  The leaves will start to fade.  Once they have yellowed, cut them off and move the bulb to a COOL DARK place where temps are about 60 degrees, such as your basement.
5. This is the point where you force the bulb to really rest and go dormant for a few months.  During this dormant period DO NOT WATER THE BULB.
6. Let the Amaryllis “sleep” for 10 to 12 weeks (3 months).
7. After 10-to 12 weeks, you are ready to start the growing cycle all over again, just the same way you did when you first planted the bulb.
8. Replace the old soil with a fresh mix.  Remove any dead leaves and old peelings from the bulb.
9. Replant the bulb again, place it in full sun and give it one good drink of water.  The combination of light and water will “wake up” the plant and encourage it to start growing again.
10. When the first little green shoots (leaves) start to emerge, (and NOT before), begin watering again regularly. 

With good care, and quality bulbs most Amaryllis bulbs will bloom seasonally for years. 

Good Luck, Deb (March 2021 Horticultural Newsletter)