Watering your lawn after an application of fertilizer is an important part of the feeding process. The water begins washing the nutrients down into the root zone where they will benefit the grass plants. Just as important, the water washes the fertilizer materials off of the tender grass blades and into the thatch below, reducing the concentration of the fertilizer, preventing chemical burn to the blades and brown discoloration on your lawn.
Follow each and every application of fertilizer with an irrigation session, whether the fertilizer applied is fast-release, slow-release or even diluted with water when applied. Washing the fertilizer compounds off of the blades immediately is critical.
Set a rain gauge or clean shallow can on the lawn in central location to measure the amount of water being put out by your irrigation system after fertilizing.
Irrigate sufficiently to drench the soil with at least 1/4 inch of water after each application of fertilizer. This will wash the fertilizer off of blades and wet the primary root zone without causing run-off of fertilizer onto the street, sidewalks or storm drain system.
Check the rain gauge to ensure that at least 1/4-inch, but not significantly more, water has been applied.