Compost is the stable, dark, and crumbly soil amendment resulting from the aerobic decomposition of organic materials. This finished product is highly beneficial for gardening, as it improves soil structure, enhances water retention, and slowly releases necessary nutrients for plant growth. For those who do not compost at home, purchasing material is a practical way to acquire this resource. Understanding the different purchasing avenues and quality metrics is key to sourcing the best compost for your specific garden needs.
Primary Sources for Purchasing Compost
Gardeners have several distinct options for purchasing compost, each offering different levels of quality, quantity, and convenience. Local nurseries and independent garden centers typically offer higher-quality, specialized compost blends, often derived from local feedstocks. These smaller retailers usually have knowledgeable staff who can provide tailored advice on which blend is suitable for your specific soil type or plant varieties.
For convenience and standardized pricing, big box stores and large hardware chains are readily available, selling compost primarily in bags. While easy to access, the selection can be limited, and the quality may be inconsistent compared to specialty suppliers. Specialized bulk landscape suppliers are the best choice for large-scale projects, as they sell by the cubic yard and can offer screened, refined material for turf or garden installations.
A cost-effective option is often available through municipal or county waste and recycling programs, which process local yard waste into compost. These facilities sometimes offer the material for free or at a reduced rate, though quality can vary depending on the input materials and the rigor of the composting process. Local farms, community gardens, or zoos may also sell or trade their excess composted animal manure, providing a nutrient-dense, localized product.
Understanding Compost Formats: Bagged Versus Bulk
The decision between purchasing compost in bags or in bulk is determined primarily by the scale of the project and available storage space. Bagged compost offers convenience, portability, and ease of transport for small gardens, containers, or minor soil amendments. While easy to store, buying material by the bag is significantly more expensive per volume than bulk and generates plastic waste.
Bulk compost is sold by the cubic yard and is the most economical choice for large areas, such as filling raised beds or conditioning an entire lawn. One cubic yard can cover roughly 100 square feet at a three-inch depth. Bulk orders require delivery, which entails a fee and a dedicated space for the material to be temporarily piled, but they eliminate the need to handle numerous small bags.
The raw material source leads to different common compost types available on the market. Green waste compost, made from yard trimmings, is a general-purpose soil improver. Mushroom compost is a byproduct of mushroom farming, often rich in organic matter. Manure compost, such as composted chicken or cow manure, provides a higher concentration of nutrients. These feedstocks result in variations in nutrient content and application suitability.
Evaluating Quality and Cost Before Buying
Quality assessment is performed through physical inspection, whether the material is bagged or bulk. High-quality, finished compost should exhibit a dark, earthy color and a pleasant, loamy smell, indicating complete decomposition. Avoid material that smells strongly of ammonia or features large, visible, undecomposed debris like plastic, wood chunks, or trash.
A mature compost is necessary to prevent phytotoxicity, or harm to plants. Maturity means the material has moved to a low microbial activity phase. Physical indicators include fine, uniform texture and an absence of heat when handled. Professional suppliers often screen their compost to ensure a small, consistent particle size, which helps with even distribution and soil integration.
For bulk purchases, ask the supplier for a compost analysis report, which may include the Carbon-to-Nitrogen (C:N) ratio. A mature compost for direct soil incorporation typically has a C:N ratio between 10:1 and 20:1. A ratio higher than 20:1 suggests the compost is immature and may temporarily rob the soil of nitrogen. When comparing costs, calculate the price per cubic foot (one cubic yard equals 27 cubic feet) to accurately compare bulk material against bagged options.