The general rule of thumb is to fertilize cool season turf grasses, e.g., bluegrass, fescue or ryegrass in the fall months and warm season grasses, e.g., bermuda, zoysia and St Augustine in the summer months. Combination products of fertilizer with pesticides can provide excellent results. However, care must be taken to use the right product for the intended situation and to follow the directions on the label. With fertilizer, more is never better.