I confess, I got this idea from my lawn guy and adapted it for my own use. Picked up 4 old screened windows from craigslist for $5 a piece. Replaced the screen with 1/2 in hardware cloth and made two framed boxes out of the four windows. Lightly tilled a patch the size of the window and planted rye grass. Did the second one after the first crop came in so they would be staggered. It didn't take long for the rye to grow and for the girls start cultivating their gardens . The hardware cloth keeps them from scratching up the grass and destroying the garden in short order. They can't reach the ground with their beaks or their feet. I just replant when needed. They certainly seem to enjoy having their own green buffet.