While there are many different materials to mulch with, two of the most common types used for landscaping design are mulch made from tree materials like shredded bark and rock mulch or yard rocks. They are both beautiful and versatile materials, and they both have different benefits and drawbacks.
Different kinds of mulch provide these benefits at different levels. The river rocks and other small stones often used to prevent weed growth in landscapes are attractive, can help conserve water and require little maintenance, but they don't nourish or insulate the soil in the same ways as conventional organic mulch.
Mulch vs. Rocks.. Many homeowners use bark mulch around plants to help retain moisture, insulate soil from cold and heat, keep weeds away, and minimize erosion. When planning your home's landscaping, it's important to consider whether to use rock or an organic mulch like tree bark for groundcover.