While they may not be your first consideration when planning your landscape, rocks add visual interest as well as serving a practical purpose. Rocks can be a focal point of a garden design, as well as add vertical or horizontal appeal. Landscape rocks can also be used for pathways, as a mulch and to help with drainage. You can use one type of rock in your design or a mix of different kinds, depending on your needs and preferences.
Wide, flat rocks with smooth but often uneven surfaces, flagstones are the classic stepping stones. They can be used in pathways or to create a stone patio. In either case, place the flagstones in a shallow trench over a bed of sand to keep them from shifting unnecessarily. The sand bed also helps prevent standing water from forming as the soil becomes impacted over time due to the weight of the stones. If you like, you can grow small plants in the cracks between stones.
Pea gravel is a versatile landscaping rock because its smooth surfaces mean it can be walked on, but it can also be used as a mulch or garden border. Because of its rounded shape and colorful appearance, pea gravel is visually striking. If used as a pathway, you need an edging to keep it in place. As a mulch, pea gravel works well for container plants and gardens, and, because it is small in size, it does not overheat the soil unnecessarily.
Coming in a wide range of sizes, boulders can be medium sized to extremely large. Boulders work well as individual visual statements, announcing either an entryway, such as the driveway onto your property, or as a central focal point of a large garden. Smaller boulders can be grouped together to add extra appeal, or stacked to create height. Larger boulders work well when placed near water gardens, as they make them appear more natural.
Ranging from 1/4 inch to 6 inches in diameter, river rocks are smooth, rounded stones, and are often flat. They can be used as a mulch for plants and also in drains, although the rocks retain heat easily, so only use them as a mulch for heat-tolerant plants. Larger river rocks can be used as decorative accents along pathways or in garden beds. You can also arrange them at the base of boulders to create a more natural appearance.