The best mulch. For five years now, I have been mulching all my vegetable beds with freshly cut lawn grass. Mulch from freshly cut lawn grass is one of the most affordable and useful ways to improve the condition of vegetable beds. When used correctly, it provides a number of advantages: Benefits of fresh grass mulch: Moisture retention: the grass layer reduces water evaporation, especially in hot weather, allowing you to water less often. Weed suppression: dense mulch blocks sunlight, preventin