First, mulches conserve soil moisture, decreasing the amount of water you need to apply. In addition, natural mulches allow rain to penetrate the soil slowly, eliminating runoff in a heavy storm. Mulches also reduce weed growth. This means less time spent weeding, freeing you to do more enjoyable jobs in your garden. Nothing dampens a gardener's enthusiasm more than the thought of spending an entire weekend weeding.
Mulches modify the soil temperature.
Clear and dark colored synthetic mulches are effective in elevating soil temperatures. The warmer soil quickens plant growth resulting in earlier yields. Light colored natural and synthetic mulches moderate soil temperatures even in the hottest summer, reducing plant stress. Finally, mulches may help to decrease disease problems in the home vegetable garden. Tomatoes, squash, and cucumbers can rot if soil-borne disease organisms splash from the soil onto the fruit.