Why Have The Flowers On My White Hellebores, Planted Last Season, Turned Green This Winter?
Bought from different garden centres. The ‘green’ plants tend to get a little more sun
Certified GKH Gardening Expert
I believe that you have started to uncover the reason, already! The green is caused by just a little too much light. These are well adapted to shade. In fact, they prefer deeper shade than many plants, and will do best in dappled light.
This article will help you to care for them: https://www.gardeningknowhow.com/ornamental/flowers/hellebore/growing-hellebores.htm