Q.Why Are My Calls Lilly Flowers Now Green?
Healthy plants began season with yellow flowers. While still prolific, the blooms are now green like the leaves and do not show up at all. They get plenty of light.
Certified GKH Gardening Expert
This is indicative of too much nitrogen in soil. This can be offset by using fertilizers low in nitrogen, but higher in phosphorus and potassium.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/bone-meal-fertilizer.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/plants-potassium.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/using-potash-in-garden.htm