Canadian Brand. This complete kit can be used to grow catnip plants indoors or outdoors in the garden. The kit contains primed catnip seeds, a peat pellet starter disc, and a sample of catnip herb. Simply add water to the peat pellet disc, sprinkle on a pinch of seeds and place in a small container with warmth and full sunlight. Transfer seedlings to a larger pot with quality soil, then if possible outside into the garden in late spring. Catnip is a perennial plant that will grow and spread throughout the garden if properly maintained. Fresh picked catnip leaves are the ultimate catnip treat for felines.