Easter lilies (Lilium longiflorum) are bulbs that have been forced to bloom during Easter. If you are given one as a gift, keep it in the house in bright, indirect light. Place it in a room with cool temperatures, 60 to 65 degrees, away from drafts and heating vents. Make sure the container has drainage holes. If it came in a decorative foil, remove the foil to allow the water to drain or cut the bottom out of the foil. Keep the soil consistently moist.
Pinching off the yellow anthers prevents pollen stains and makes the blossoms last longer. Once the flowers are past their prime, remove them.
Easter lilies are true lilies, hardy to zone 4. Here in the DC metro area, you can put your plants in your garden in May after the last frost. Plant them in full sun, in well-drained soil. Plant them at the same depth as they were in the pot. Ideally 3 inches deep with 12 to 18 inches between plants. Treat them like perennials — leave the foliage on until eventually the plants become dormant for the winter. In the spring, fertilize with a slow-release balanced fertilizer or use an organic fish fertilizer.
It may take a year or two for the bulbs to bloom again. However, they will not bloom at Easter, they will bloom in the summer. In nature these are summer bloomers, like other garden lilies.