Q.Hello, I have a black Lilly plant! I planted the bulb last March and it grew up and was very healthy during the summer. After the
summer I had to change the pot cause the first one was very small . Now all the leaves are turning into yellow. How can I save my plant ?

Certified GKH Gardening Expert
As a member of the lily family, it will need a yearly dormancy. This means sustained temperatures around 45F or roughly 7C for several weeks to a couple of months. Even if the cool temps are not met completely, they will still need to remain dry for the dormancy. Only a small spoonful of water on occasion will be plenty.
The better option will be forcing dormancy.
This article will help to force dormancy, and store the plants for winter: https://www.gardeningknowhow.com/ornamental/bulbs/bgen/preparing-bulbs-for-winter-how-to-store-bulbs-for-winter.htm