Stepping stones create a functional walking surface and introduce a decorative element into a landscape. The material used to fill the spaces between these stones significantly influences the final look, dictates the path’s drainage capacity, and determines the maintenance required. Selecting the appropriate filler balances aesthetic preference with practical considerations, ensuring the path remains stable and complements the surrounding garden or yard.
Non-Organic Fillers
Non-organic fillers are inert materials prized for their stability, longevity, and minimal maintenance requirements. Gravel is a common choice, available in different forms. Pea gravel consists of small, smooth, rounded stones (1/8 to 5/8 inch). While it provides excellent drainage, pea gravel shifts easily underfoot and requires a physical border. Crushed stone, or angular gravel, offers superior stability because the sharp edges interlock and resist displacement, making it better for higher-traffic areas.
Finer stone products provide a more consolidated surface. Decomposed granite (DG) is finely weathered granite that, when compacted, creates a durable, semi-permeable, firm surface with a refined appearance. Polymeric sand is a blend of fine sand and a polymer binder that hardens when exposed to water. This material locks stones and inhibits weed growth, offering a low-maintenance solution.
Sand is frequently used as a leveling base beneath the stones but is ineffective as a standalone gap filler because it washes out easily and encourages weed growth. When using non-organic fillers, placing landscape fabric beneath the path prevents the filler from sinking into the subsoil and suppresses weed germination. Keeping the filler material slightly below the stepping stone surface helps prevent scattering.
Organic Fillers
Organic fillers are natural materials that decompose over time, requiring periodic replenishment. Shredded or chipped mulch and wood chips are the most common selections, offering a softer, rustic aesthetic that integrates well into natural garden settings.
Wood chips suppress annual weeds, conserve soil moisture, and moderate soil temperature. As they break down, they contribute organic matter and nutrients to the soil. However, decomposition requires the material to be topped off every one to two years to maintain the fill level.
Wood chips and mulch can retain excessive moisture, potentially encouraging mold or attracting insects in poorly drained areas. Furthermore, because the material is lightweight, it can be washed away in heavy rain or migrate out of the path, necessitating physical edging for containment.
Living Groundcovers
Living groundcovers introduce soft texture and color, offering the highest aesthetic impact. This option requires specific environmental conditions and is best suited for paths with light to moderate foot traffic. Suitable plants must be low-growing, creeping varieties that tolerate occasional compression, such as creeping thyme, Irish moss, or sedums.
Plant Examples
Creeping thyme is popular for its aromatic foliage and resilience to moderate foot traffic, thriving in full sun and well-drained soil. For shadier spots, Irish or Scotch moss (Sagina subulata) creates a dense, soft, carpet-like effect that handles foot traffic well. Sedums, or stonecrop, are highly heat- and drought-tolerant, making them ideal for sunny, exposed locations.
Successful installation requires adequate spacing between the stones, typically at least two to three inches, to allow plants room to spread. The spaces must be filled with a well-draining soil medium, not just sand, to support growth. Once established, these plants inhibit weed growth but require initial care, including watering and light trimming.
Installation and Preparation Considerations
A stable path requires thorough preparation of the base beneath the stepping stones. The area must be excavated to a depth that accommodates the base layer and stone thickness. The final surface should be level with or slightly above the surrounding grade for proper water runoff. A compacted sub-base, often two to three inches of crushed stone or paver base material, is paramount for stability.
This crushed material must be thoroughly compacted with a tamper to prevent shifting or settling. Following compaction, a thin layer of coarse sand or stone dust is spread and leveled to provide a bedding layer. The stones are then placed and tapped into the bedding layer with a rubber mallet to ensure they are firmly seated and level.
Weed control involves installing landscape fabric over the compacted sub-base before adding bedding material. This barrier minimizes weed growth from below while allowing water to permeate. For loose fillers like gravel or mulch, physical edging (metal or plastic restraints) is necessary along the path’s perimeter to prevent material migration. The path should also be graded with a slight slope away from nearby structures to ensure effective surface drainage.