I would like to provide wheat grass for my SILKIES ,who will not be free range . They will have 2 runs attached to their coop. I know that there are "kits",which are meant for housebound cats and are expensive. Where can I purchase the wheat grass and possibly grow it in a cat litter pan that I will purchase at one of the "super marts "?Would a "natural store" sell it? Or would I look in a garden place? I want to grow the grass in the above mentioned container. Does anyone have any further insight on what I would like to accomplish? Thank you!