I use deer/bird netting around my holly bushes to keep the chickens from eating the berries. I wrapped them twice. While the hens could technically stick their beaks through the netting holes, mine do not. In fact, they now seem to ignore the bush altogether. When I first began to free range them I had to run them away from the bushes. I think they must acknowledge the obstacle and decide it would simply be easier to peck something else. Maybe you could try that too?
I also have hostas around my qoi pond. The hens have yet to peck them, but should they start to I'll just get those mini white pickett fences sold at the dollar store. They're about a foot tall and slide into the ground with thin stakes. Can easily be removed when hens go up at night or left for decoration.
DH and I have a section of the yard where we don't cut the grass as often as the rest. This is the 'chicken patch' they like to forage in it and my GLW loves to eat the seeds off of one particular type of grass when it grows tall. They spend a lot of their time here. Maybe have a pile of leaves for them to dig around in (my hens love leaves!) or sprinkle around some scratch grains in a particular section of the yard so they'll scratch around there looking for goodies....also, maybe limit the time they're ranging so they don't have as much time to get into trouble. HTH