Mulch can prevent weeds, both by denying the sunlight that triggers germination of seeds, and by acting as a physical barrier between seeds and the soil. And, unlike artificial landscape fabric, it fertilizes the soil (in the case of organic mulches like compost, manure, grass clippings, and aged wood chips). Both sandy and clay soils need mulch in the flower garden. Mulch helps sandy soils retain the moisture that drains quickly away, and clay soils get the benefits of aeration from increased earthworm activity.
