Whether you fertilize your lawn once a year or a garden every two weeks. you want the nutrients that you purchase to get to the plants' roots. Water provides the energy that carries nutrients down to the growing ends of the roots and then up through the plant to the growing blades, branches or leaves. When and how much water is used on that pricey fertilizer determines how effective it will be.
Lawn fertilizers are applied mixed with water using a hose-end applicator, delivering all of their nitrogen at one time. Dry, timed-release, or slow-release nitrogen fertilizers, require water applied as quickly as possible -- within 48 hours after application. If herbicide is included, though -- in a "weed and feed" -- water should be withheld for 48 hours until the herbicide has time to work. Instructions on containers might vary, but you should water deeply after fertilizing. Grass roots grow about 3 inches deep, so water should wet the ground down to that level. Sandy soil requires less but more frequent irrigation than loam or clay soils.
Fertilizers for Gardens
Fertilizer for flowers and vegetables typically contains balanced nitrogen, phosphate and phosphorus, according to plant needs. These fertilizers should be watered in immediately to carry nutrients to roots. Fertilizers with pre-emergent herbicides, called "weed preventers," form a barrier beneath the soil to prevent germination and also need water immediately to set up a barrier below the soil's surface. Whether watering lawn or flower gardens, though, avoid over-watering, which washes fertilizers into storm drains that empty into waterways.
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