I give my older cat Mollie Rose kitty grass. I buy it at the pet store, it's called Cosmic Cat Grass. All you do is follow the directions and within 5 days you've got grass. Kitty grass helps with their digestive system. It also helps them if their stomach is upset. I don't give it to her on a regular basis, though. Also, beware of one type of grass that's sold. It comes in a square plastic container. You peel back the top and add water to it (the grass seeds are in some sort of gel mixed in with the soil). I tried it once and Mollie actually ate the gel and she got real sick. It irritated her throat and made her miserable. Personally, the best way (if you're not lazy like I am) to grow grass is to buy the Cosmic Kitty Grass Seeds, potting soil and plant it yourself. Put it in a nice sunny window and VOILA!! You have kitty grass. Every once in a while, cut it back and it will grow fuller (like the lawn you hate to mow). If you grow it yourself, there are less problems.