Herbicides work several ways to kill unwanted weeds. Weed and Feed contains a post-emergent herbicide, one that acts on weeds that already exist. Crabgrass Preventer contains pre-emergent herbicides that work by keeping seed from germinating and developing. Dry lawn fertilizer is easy to apply using either a rotary or drop spreader. Rotary spreaders have the advantage of covering wide areas with each pass.
Drop spreaders are more accurate, but requires more walking.
Whether you use a rotary or drop spreader, consider fertilizing at half the recommended rate. Then go back over the same area again, crossing your first paths. Look on the fertilizer bag to find the setting for your spreader. Ideal weather conditions would be a cool, calm day, followed by rain or watering. Lawn Fertilizing Options High maintenance lawns need 3-4 applications spaced throughout the season.