Even cats need fiber in their diets, and supplemental grass makes for happy felines. They also get trace minerals and vitamins from grass, and [hack~hack] it helps with hairballs.
It is easy to grow, so I try to keep a bit on hand for the boys. Unfortunately, it grows fast, dies out fast, and requires frequent replanting to assure a regular supply, but seeds planted today can be ready in three, four days for nibbles.
It isn’t necessary to grow a lot at one time, though I have tried growing it in a large enough container that a large cat (Louie the ginger cat, at 24 pounds, 10.82 kg) could lounge in it without having to go outside or wait for the warmer seasons when grass flourishes outside.
That was too alien for the boys, though. Bat the grass with one’s paws. Eat the grass. Sniff the grass. But lie in the grass! They are “city sheepies”! What do they know about such things?