I have it on good authority that chickens are not fond of asphalt or concrete unless you break it up into small pieces for them.You can't really have them not do that. Yo might want to get less great 'foragers' next time you add to your chicky ranks. Best thing you can do is fence them out of the place you want to grow stuff. Contain them with chicken wire, or contain them out? Google 'chicken gardens' it might help?
Almost nothing although I've found a few weeds they apparently won't eat as they're growing in their run. Rhubarb, they don't eat it much but they love to scratch around in it and tear up the crowns. Mostly, it they don't eat it, they tear it up with their scratching and digging for bugs & worms. I have some fruit trees planted in the chicken run and there's not a green leaf growing within hopping range of the chickens. Regards, WoodyWhat can I plant that they WONT eat? I've got a lot of fertile land and lots of sunshine. I want to get planting!