How can mulch suppress weeds in a garden?

Mulch suppresses weeds in a garden primarily by creating a physical barrier that prevents weeds from accessing the resources necessary for their development. By covering the soil surface, mulch blocks sunlight, which inhibits the germination and growth of weed seeds that require light to thrive.

This method functions similarly to the principle of a smother crop, where plants are sown densely to shade and "choke out" weedy growth by competing for space and light. By effectively depriving weeds of these essential environmental conditions, mulch serves as a highly efficient, non-chemical tool for maintaining garden health and reducing the labor required for manual weeding.