The figure below and the photographs of the chrysanthemum flowers show how temperature affects flower colour. What happens in other flowers, such as chrysanthemums also happens in daylilies.
The higher the temperature (above the optimum) the less pigment (the lighter the colour). The lower the temperature (above the optimum) the more pigment. Sunny days versus cloudy days (if there are enough of them) also change the amount of pigment.
