Mechanism of action: Phosphorus is one of the major plant nutrients in the soil. It is a constituent of plant cells, vital for cell division, development, photosynthesis and respiration. Phosphorus supports the transfer of energy throughout the plant, stimulating and enhancing bud development, seed formation and blooming.It helps strengthen young roots and gives them a strong start. How to use: Alfalfa and perennial grasses: Apply 9 gram per square feet, 1 - 2 inches below the seed at planting to ensure good root development and seedling establishment. Flowering plants: For new annual (petunia, marigold, etc) & perennial plantings (rose, lily, etc): Broadcast 135gram per square feet & incorporate into the top 4 - 6 inches of soil during flower bed preparation. Make a second application at the same rate 6 to 8 weeks later. For established plants: Spread the same amount around the plants and work it lightly into the soil to avoid disturbing plant roots. Make a second application at the same rate after 4 months.