the andersons professional pgf complete 16-4-8 fertilizer with humic dg 5,000 sq.ft. the andersons pgf (professional grade fertilizer) takes all the research, top products, needed nutrients, and combines them into one bag. doc has spent the last year testing and working with the andersons plant nutrient group to develop an all in one complete, professional grade fertilizer, and make it available to the average homeowner. now you... can use the same quality products that are used on golf courses and sports turf around the world. one 18 lb bag covers 5000 sq ft of lawn. great for all seasons, spring, summer and fall. apply every 6-8 weeks during the growing season. for summer application on cool season grasses apply at a 75 – 50% rate.