My chickens have devoured every green blade in their run. It's no use planting grass there as they will just rip it up? What do you do to solve this? As I am not always there to supply them with it? I would need a small-scale suggestion as I only have four hens (I am getting more this year). So what is best? Pots...or boxes.. or cartons? Pics would be appreciated! Thanks in advance!