A. The numbers refer to the percentages of nutrients in the fertilizer: nitrogen, phosphorous and potassium.
Different types of grass and plants require different levels of nutrients. Nitrogen encourages growth in small amounts, but too much can damage your lawn. Phosphorous plays a role in the rooting and setting of flower buds. Potassium is a key nutrient for overall plant health.
By referring to the nutrient mix on the bag, you can determine which fertilizer is right for your lawn or garden.