My main run is just bare dirt, nothing in it at all. Between their poop build-up which burns new growth, them eating any new growth, and especially their scratching there just isn’t any green stuff in here at all. On occasion I’ll confine them to this main run but that is really rare. I think it is the scratching more than anything else that keeps it clean.
The larger area pretty much stays green during the growing season. When the grass first starts growing in the spring I’ll confine them to the main run about a week to a week and a half to let it get established. During the winter the green stuff is not growing so it can look really barren but it comes back in the spring.
When they are foraging in that big area they eat certain things and leave other things alone. I have to occasionally mow that area to knock down the stuff they won’t eat and give the stuff they do eat a chance to grow. I don’t have morning glory in that area but there are somethings that are poisonous to chickens. They have to eat it before it harms them and mine don’t.