As a groundhog war veteran I can only tell you that nothing ever deters them. The only solution is to trap and relocate -- IF there is no rule against that where you live.
That said, here are a few plants they have not touched in my garden:
Astilbe, hibiscus, peonies, irises, thyme, lavender, day lilies, asiatic lilies, hosta, burning bush, roses, rhodys, azaleas, japanese maples, japanese blood grass, bee balm.
GL!
