To a chicken, the whole world is its salad bowl, and underneath that is its dust bath tub.
To keep both chickens and flowerbeds, you will need to fence either the chickens or the flowers. Or both.
One thing that has worked is to place flat heavy things around the roots of the plants, pieces of board, tile, pavers, etc. Then when the chickens dig they won't uproot the plants. This may compromise the plants' ability to get watered well. And it doesn't prevent the birds from eating the leaves if they find them particularly tasty. I have done this with larger perennials in my bird-and-butterfly garden, and now that they're well rooted the birds don't bother them.
I don't know how well that sprinkler would work to discourage chickens, let us know if you try it.