Answer: I think what you are seeing is pretty normal. Both the Japanese maple and fothergilla are deciduous, which means they will turn color and drop all of their foliage every year in the fall. They should grow new leaves next spring.
Solomon's seal is an herbaceous perennial, meaning it dies back completely in the fall and regrows anew from its roots in the spring each year. As the weather turns colder it will discolor and the stems will die back. Once they are dried out, you can clip them off at ground level if you wish. If they are growing in a more casual garden or naturalistic setting you can leave them where they fall, the leaves and stems will provide a bit of natural mulch for the plants and help feed the soil.
Enjoy the seasonal changes in your garden!
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