Grow your own cat grass to satisfy your cat's natural cravings for a yummy veggie snack. Grass seeds are easy to grow; you can grow them right in the container they come in. Open lid Wet the granules with 2.5 cups of lukewarm water evenly. Water only once. Put the container in a warm; light place; avoiding direct sunlight. After 3 days the grass will begin to germinate. Within 8 days the clipping opens up and the grass can grow to its full height. When the grass has reached a height of 2"-4" you can serve it to your cat.