Compost serves as a fundamental soil amendment, introducing organic matter and beneficial microorganisms necessary for successful gardening and landscaping. Unlike simple fertilizers, good compost physically improves soil structure, enhancing water retention in sandy soils and improving drainage in heavy clay. This guide will walk you through the practical choices of securing the right compost for your project, focusing on purchasing in convenient bags or cost-effective bulk quantities.
Understanding Different Compost Types
The material used to create compost heavily influences its final characteristics and best applications. Mushroom compost, a common by-product of the commercial mushroom industry, is typically composed of materials like straw, horse manure, and gypsum that have been pasteurized and used as a growth medium. This type is generally rich in organic matter, helping to improve soil structure. However, it can be slightly alkaline due to added chalk or limestone, making it less ideal for acid-loving plants.
Manure-based composts, derived from aged or composted livestock waste, are prized for their balanced nutrient profile, including nitrogen, phosphorus, and potassium. Proper composting is necessary to reduce the risk of burning plants with excess nitrogen, kill weed seeds, and eliminate pathogens. Worm castings, or vermicompost, are the nutrient-dense excrement produced by composting worms, offering a highly concentrated source of beneficial microbes and water-soluble nutrients. These castings are often used as a soil conditioner or top dressing because the nutrients are readily available for plant uptake.
Purchasing Compost from Retailers and Local Programs
For small-scale projects like container gardening, top dressing small flower beds, or amending a few planting holes, purchasing pre-bagged compost is the most convenient option. Bags of compost are widely available at big box home improvement stores, offering easy transport and storage. Independent garden centers often stock higher-quality, specialized blends, such as organic or regionally produced mixes, along with knowledgeable staff to offer guidance.
Bagged compost offers guaranteed consistency and cleanliness, as it is typically screened and packaged under quality control standards. Many local municipal or county solid waste programs also process yard waste and offer finished compost to residents, sometimes at a reduced cost or even free of charge. These local programs are an excellent source for general-purpose soil amendment, though the quality can sometimes be more variable than commercial products.
Sourcing Compost in Bulk
When undertaking large landscaping projects, filling raised garden beds, or amending a substantial portion of a lawn, buying compost in bulk becomes the practical choice. Bulk compost is sold by volume, typically measured in cubic yards, and is sourced from landscape supply yards, local soil and gravel companies, or specialized topsoil producers. One cubic yard is a significant quantity, equivalent to 27 cubic feet of material.
Ordering bulk material requires planning for delivery, as the supplier uses a dump truck to deposit the compost at your designated location. This option demands sufficient space for the delivery vehicle to access and safely offload the material onto a tarp or driveway. While bulk purchasing offers significant cost savings per unit volume compared to bagged products, be aware that many suppliers enforce a minimum order quantity, and delivery fees are usually separate from the material cost.
Comparing Cost and Quantity Measurements
The fundamental difference in purchasing compost lies in the measurement units: bagged products are sold by the cubic foot or quart, while bulk products are sold by the cubic yard. To make a meaningful cost comparison, you must convert the price of a bag into a cubic yard equivalent. Since one cubic yard equals 27 cubic feet, calculating the number of bags needed to reach that volume is necessary for accurate pricing.
Calculating your volume need beforehand is necessary to avoid over-ordering or making multiple trips. A common garden application, such as top dressing a vegetable garden, typically requires a layer of compost between one to three inches deep. To estimate the volume, multiply the area of your project (length multiplied by width) by the desired depth in feet, then divide the resulting cubic feet by 27 to find the cubic yards needed. Bulk compost is nearly always more cost-effective for large volumes.