Perennials are heavy feeders and since they stay in one spot for a number of years, they require liberal feeding of complete plant food. Feed established plants early fertilzer in the spring, as soon as they appear above the ground. Use 1 pound (1 pint) of fertilzer per 25 feet of row or 25 square feet of area. Work plant food into the soil around the plants. Feed at the same rate every 8 weeks during the growing season.