Kittens can start eating cat grass around two and a half or three months old. However, this timing is not absolute, as it depends on the kitten's specific situation, such as its digestive health, growth rate, grooming frequency, and shedding.
If your cat is a long-haired breed that frequently grooms itself and sheds a lot, it needs to start eating cat grass even if it's only two or three months old to help expel hair. If cat grass isn't effective, you can consider giving your cat hairball remedy to protect its digestive system and help expel hair.
For short-haired cats that don't shed much, if they don't like to groom themselves, you can wait a little longer before feeding them cat grass, or you don't need to feed them frequently.
If your cat is experiencing gastrointestinal problems such as inflammation, bloating, or the accumulation of necrotic tissue, you should feed them cat grass to help alleviate these symptoms.
