I use Wheat seeds that I find in most bulk sections and always in a health food store… (it’s often called ‘hard winter wheat’ or sold for making wheat-grass juice).
Start by soaking about 1/2 cup seeds (depending on what size container you’ve chosen), in enough water to cover, overnight.
The next day:Put the seeds into a jar with a good lid. For the next 2 or 3 days you’ll be rinsing the seeds and sprouts at least twice a day. Once the seeds have germinated you’ll need to plant them. Sprinkle the sprouted seeds evenly over the moistened fibre/soil.
Make sure the sprouts and soil are moist and then cover with plastic wrap. A clear plastic bottle with the top cut off works well too, depending on the container…Now just wait a few days….be sure to keep everything moist…your cat will love it!