I operate a pest control company and I was approached by one of my commercial customers for bid for a fertilization and weed control program. I got the bid and the management gave me a spec sheet with exactly fertilizer to be used for the lawns and ornamental beds, and what pre-emergents to use for the lawns and ornamental beds. A few of my friends with landscape companies are now referring thier customers to me for fertilization and weed control applications. I have all of the proper certifications! My question is how do I choose the appropriate fertilizers for my residential customers? Do I test the soil? What exactly is a "four-step" program? Does it mean four applications of fertilizer/pre-ermergent/pesticide per year (spring, late spring/early summer, late summer/early fall, and a winterizing application)? I want to know exactly what I am doing before I commit to any residential lawn customers (if I do commit to this add-on service). I used to fertilize relative's lawns when I was younger, but I just chose fertilizer that seemed to be the most popular in the store. Thanks for your information!