Deciding what type of fertilizer to use can be a bit confusing. Let the numbers and the labels on the bag be your guide. Fertilizer labels often tell you the type of plant it is best for. For example, lawn fertilizers generally contain high levels of nitrogen (first number) to promote vegetative or leafy growth. Lawn fertilizers are great for your grass, but lousy for annual flowers (too much nitrogen promotes excessive vegetative growth and inhibits flowering). General purpose fertilizers are often complete (contain nitrogen, phosphate and potash) and are good for a wide range of plants in the garden, landscape or containers.