Applying lawn fertilizer correctly is crucial to its effectiveness. Some fertilizers should be applied to your lawn when it is dry. These include regular fertilizers and fertilizers containing pre-emergent herbicides. They need to fall down to soil level, and wet grass prevents that because the granules stick to the wet foliage. Lawn fertilizers that contain post-emergent herbicides, such as weed and feed, need to be applied to wet grass. This allows the granules to stick to the weed foliage and kill the weed. Apply these fertilizers is in the morning when dew is still present on the grass.
Water the lawn if it is not already wet. Set up sprinklers and irrigate until the foliage is soaking wet.
Fill the hopper of your broadcast spreader with weed-and-feed fertilizer. Read the manufacturer's instructions for the correct application rate and set the dial on your spreader to that setting.
Push the spreader in front of you and walk in straight, parallel paths across your lawn to dispense the fertilizer. Continue until the entire lawn is covered.
Refrain from walking on your lawn for two days to allow the granules sufficient time to kill the weeds. Walking across the lawn may brush the granules off of the weeds.