Landscaping stone, or aggregate, provides both structural function and aesthetic appeal in outdoor design. These hard materials create durable, low-maintenance surfaces while assisting with soil stabilization and managing water runoff. Selecting the most suitable stone involves assessing the desired look, the stone’s physical properties, and the specific demands of the project area to ensure long-term performance and beauty.
Common Types of Landscaping Stone
Crushed stone and gravel are mainstays in landscape design, differentiated by their texture and shape. Crushed stone, such as crushed granite or limestone, features jagged, angular edges that interlock tightly when compacted, providing superior stability for high-traffic areas. Pea gravel consists of small, rounded stones, typically 1/4 to 3/8 of an inch, which are smooth due to natural weathering. This roundness makes pea gravel more comfortable underfoot, though it is prone to shifting.
Decomposed granite (DG) is a fine-textured aggregate resulting from weathered granite breaking down into silt-like particles and small fragments. Available in warm tones like reddish-tan, gold, and gray, DG offers a soft, earthy appearance that blends well with natural settings. DG can be highly compacted, especially when a polymer stabilizer is introduced, creating a firm, semi-permeable surface.
Flagstone and natural pavers are quarried sedimentary rocks like slate, sandstone, and limestone, prized for their naturally flat, layered structure. Sandstone often presents in earthy hues and has a textured surface. Slate is known for its durability, fine grain, and darker color palette. Limestone and bluestone offer a sophisticated appearance, with the natural cleft providing excellent slip resistance.
River rock and beach pebbles are characterized by their smooth, polished surfaces, the result of constant water erosion. River rock tends to be larger, often ranging from one inch up to several inches in diameter, and comes in varied colors like brown, tan, and gray. Beach pebbles are typically smaller and more uniform in color, often used as decorative accents for a clean, modern aesthetic.
Lava rock, an igneous stone formed from cooled volcanic material, possesses a porous structure that makes it exceptionally lightweight compared to other aggregates. This porosity also contributes to its thermal and drainage properties. It is commonly available in dark shades of black, gray, and deep red, providing a striking contrast against greenery.
Selecting Stone Based on Application
For patios and walkways, stability is paramount to support furniture and foot traffic, making angular crushed stone or stabilized decomposed granite ideal choices. The sharp edges of crushed stone lock together to form a solid sub-base or surface. Stabilized DG compacts almost like concrete, offering a firm, natural-looking path. Flat, irregular flagstone is also excellent for walking areas, as its large, planar surface provides a stable, aesthetically pleasing surface with natural grip.
Ground cover and mulch alternatives benefit from materials that suppress weeds and conserve soil moisture. Lava rock and decorative gravels are effective, forming a permanent barrier that inhibits weed growth without decomposing like organic mulch. The porous nature of lava rock allows water to pass through to the soil while insulating the roots and preventing rapid evaporation.
Drainage and erosion control demand materials with high permeability that allow water to flow freely without washing away the stone. River rock is particularly suitable for dry creek beds and drainage ditches because its smooth, rounded shape minimizes friction, allowing water to pass quickly. Larger river stone and specific types of drain rock are often used in French drains, where voids facilitate rapid water movement away from foundations or saturated areas.
For borders and edging, the stone’s size and visual impact are the primary concerns for defining spaces and adding contrast. Large river rocks or small boulders are effective for creating a clear separation between a lawn and a garden bed, providing a weighty border. Mexican beach pebbles or other decorative aggregates can be used to create clean, defined lines around features or to topdress container plants.
Practical Considerations for Stone Selection
The final choice of landscaping stone is often influenced by cost and regional availability. Quarry-sourced crushed stone and gravel are generally the most affordable options, especially when purchased in bulk by the cubic yard or ton. Specialty materials, such as imported Mexican beach pebbles or specific types of flagstone like bluestone, carry a higher price tag due to transportation costs and limited sourcing.
Maintenance and durability are long-term considerations that affect the stone’s longevity. Unlike organic mulches, stone does not decompose, making it a permanent solution, but some stones are more susceptible to weathering. Softer sedimentary stones, like certain types of limestone and sandstone, can be prone to staining or may flake over time due to freeze-thaw cycles. Decomposed granite, while durable, may require occasional replenishment or re-compaction to maintain its level surface in high-traffic areas.
Climate impact and heat retention should be assessed, particularly in sunny environments. Dark-colored stones, such as black lava rock or dark slate, absorb and retain more solar radiation, which can raise the ambient temperature around plants. Conversely, lighter stones, including pale limestone and white marble chips, reflect more sunlight, helping to keep the surrounding area cooler, a benefit for pool surrounds or seating areas.
Installation effort is a final practical measure, as the labor varies considerably between materials. Spreading a layer of pea gravel or lava rock is a simple task that requires minimal specialized equipment. Laying flagstone, however, demands more precise preparation, including leveling the sub-base and often setting the stones in a bed of sand or mortar, which increases the labor and time required.