My kitty, Meia, loves cat grass (Avena sativa, or the common oat) and it's so simple to grow in just a small pot in your window or in a large planter on your deck. There are no real answers, even by vets, as to why cats eat cat grass, but either way your kitty will go nuts over the lush grass that comes from it and it's also a great way to get them to add more fiber into their diets.
This is one of my favorites to use. It's from a company called, Botanical Interests and they have some of the best seed selections I've seen online. You can purchase your seeds from BI, here.
Just add soil to a simple pot or planter, add the seeds and cover with soil. Done!
In just a short time you will have cat grass growing for your kitty to munch on. Be sure to mist once a day to help keep the soil moist.
Meia loves it! I will sometimes catch her laying in the pot with the grass, she just loves it that much. Ha!