The cost comparison between landscaping rock and organic mulch depends on their different cost structures. Both materials serve as ground cover, suppressing weeds and improving aesthetics. Comparing the two requires considering volume versus weight, installation complexity, and the necessity of recurring replacement, rather than just the sticker price.
Upfront Material Cost Comparison
The initial purchase price is difficult to compare directly because materials are measured and sold differently. Organic mulch, such as shredded hardwood or cedar, is typically sold by volume in cubic yards. Standard hardwood mulch costs between $30 and $65 per cubic yard, while premium cedar mulch can reach $100 per cubic yard.
Landscaping rock, like pea gravel or river rock, is sold by weight in tons. Decorative rock is generally priced from $20 to $70 per ton, with higher-end river rock costing $80 to $280 per ton. To accurately compare costs, a standardized coverage area must be used, such as covering 100 square feet at the recommended three-inch depth.
A cubic yard of mulch typically covers about 100 to 108 square feet at that depth. Conversely, one ton of standard landscaping rock covers approximately 80 square feet. Based purely on the initial material cost required to cover a given square footage, mulch is almost always the less expensive option, especially for large projects.
Installation Costs and Necessary Preparation
The cost disparity widens when factoring in preparation and labor. Mulch requires minimal ground preparation, usually just clearing debris, and its light nature makes spreading straightforward. Professional installation labor for mulch is quick, often costing around $1.50 to $2.75 per square foot, including the material.
Rock mandates the installation of a high-quality geotextile weed barrier to prevent stones from sinking and to stop weed growth. This commercial-grade fabric is an added material expense, costing between $0.15 and $0.50 per square foot. Rock is also heavier and more cumbersome to transport and spread, which increases labor costs. Professional rock installation can reach a total cost of over $4.00 per square foot, making the upfront installation of rock significantly more expensive than mulch.
Long-Term Expense: Replacement and Maintenance
The calculation of long-term expense is where rock shows its financial advantage. Organic mulch is biodegradable and decomposes over time, which benefits the soil but requires constant attention. Mulch typically needs to be replenished annually or bi-annually to maintain the necessary three-inch depth for weed suppression and soil moisture retention.
The material and labor costs for mulch are recurring expenses that accumulate over time. Rock, being an inert mineral, does not decompose and is considered a permanent ground cover that rarely needs replacement. While rock does not require new material every year, it does require periodic maintenance, such as cleaning, to remove debris and prevent soil buildup that allows weeds to take root.
Professional rock maintenance, involving cleaning and restoring the area, can cost around $2.00 per square foot, though this is only needed every few years. The most significant maintenance cost for rock is the labor-intensive process of removal, which can cost $50 to $200 per cubic yard if the landscape design is changed. Over five to ten years, the repeated purchase and spreading of mulch will eventually surpass the one-time installation cost of rock.
The Total Cost Verdict
Mulch offers the lowest initial expenditure because the material is cheaper and the labor for spreading is less intensive than rock. Organic mulch is the most economical choice for a project budget focused only on the first year. This benefit holds true for homeowners who plan to move within a short timeframe, such as two to three years.
Rock is the more cost-effective choice for a long-term investment due to its non-degradable nature. Since rock only requires the one-time installation cost and minimal recurring material expenses, it typically becomes the cheaper option after approximately three to five years. For a homeowner committed to a property for a decade or more, the recurring annual cost of refreshing mulch will outweigh the initial investment of a rock landscape.