What do you do with a lily after blooming season is over?

After the blooming season of a lily is over, allow the foliage to remain until it turns yellow and dies back naturally, as this helps the bulb store energy for the next season. Once the leaves have died, you can trim them back to the ground. Additionally, consider applying a layer of mulch to protect the bulb during winter. If the lilies are in a pot, you can either leave them outside if your climate permits or bring them indoors for the winter.