Just catching up with this Lurching, apologies, I'm slow...
Cat grass is different from cat nip, I think it's just like the stuff you get out in the park?.
I'm growing catnip again ( a member of the mint family) that drives the furries aff their wee furry drugy heids

This is a big success, I did it a few years back in a big ole heavy terracotta pot. It was much loved. However we moved house and the resident cat population abused my boys natural mama grown herbals and it died of too much cat partying.
So I've started off all over again. Seamus the rat cat has already eaten half the seedlings - but I'm going for the same format super huge heavy terracotta pot and this time I'm covering it with a chicken wire dome so bits can grow throw and be enjoyed but the plant itself can hopefully be saved and continue to grow. It takes ages to grow btw...
Not sure if that answered your question?
If you want your cat to enjoy a pint and spliff go for cat nip.
If you want your cat to have his greens and good digestion get cat grass ( like a lump of turf and grow it long).