Every two months here in peacock graced (or infested depending on your opinion ) Arcadia I get inquiries about what plants they will not eat. First off, peacocks will dig up newly planted small container plants just to get at the grubs and insects that the newly transplanted plant's injured roots attract; second peacocks like the new foliage of plants they may not necessarily feed on once the foliage has matures. The best thing to do with flowers is to establish them in area that has been surrounded by bird netting. If you can't do that then try using a motion detecting scarecrow to do the job; but be careful, I once almost gave a UPS delivery man a heart attack when my motion detecting scarecrow went off without warning and scared the daylights out of him.
Here is a list that has been compiled over time here at the Arboretum of plants that are resistant to peacocks.
Bird of Paradise
Blazing Star Liatris
Hen & Chicken