The paperwhite foliage remains green even after the last flower has wilted and died because the leaves are still absorbing sunlight and nutrients to replenish the stores in the flower bulb. Prune away the dead flowers but leave the leaves on the plant until they yellow and die back on their own. Provide the plant with plenty of sunlight by placing it near a brightly lit window. It typically takes about six weeks for the foliage to begin dying back naturally, at which time it’s OK to remove it.
Paperwhites rarely flower again in a pot because the forcing process is too stressful. Transplant the paperwhites outside after all frost danger passes in spring, often after the foliage has died back and the bulbs have gone dormant. Plant the bulbs in a sunny, well-drained bed. Sow each bulb with the pointed top 2 inches beneath the soil surface and space the bulbs 6 to 8 inches apart. The bulbs require no care during summer and winter dormancy, but will require regular watering once they send up new growth the following spring.
Make sure to store the dormant bulbs away from fruits and vegetables, as they release a gas that harms the bulbs.