You can cut back the stems and flowers in late spring or whenever the hellebore plant is done blooming and the flowers have faded. You do not have to cut back the faded blooms as the plant will be fine if you ignore this and leaving the faded blooms means you are more likely to find hellebore seedlings near the mother plant sprouting from fallen seed. Always cut back the stems and blooms if they show signs of disease. Dark black lesions on the stem or flowers that turn black and become distorted are signs your hellebore are being attacked by a fungal infection. Cutting back the old hellebore leaves in early winter is one way to discourage infection from fungus among us and cutting back stems and flowers that look diseased is also the best defense from spread of the fungi.  One more thing - if your hellebore plant has been in a pot for several years it may need to be transplanted into the ground unless the container is very large - at least 24 inches deep as and wide. Hellebore have thick but brittle roots and they hate to be moved. Sneaking it out of a container without breaking the roots can be difficult if the plant has overgrown the pot. In that case, maybe you do want to leave the faded blooms and watch for seedlings so you'll have young plants to replace the mother plant in a few more years. Hellebores live long in the ground, live for years in large containers but may decline in smaller pots after three or four years. Keep growing, Marianne Binetti