How to Buy Top Soil, Compost, or Mulch in Bulk

You may be looking to redesign the landscaping at your home, develop your garden, or have a property that needs a massive amount of soil, mulch, or compost for whatever reason. In that case, the hardware store or garden center may not have enough or offer the best prices.

In considering the different soil options, it’s important to calculate how much you need, understand costs, and think about the logistics of having it delivered. You will likely find that buying soil, compost, or mulch in bulk is quicker, cheaper, and, ultimately, the right decision for you.

Consider the 3 Major Soil Products

In landscaping, gardening, or any major project involving soil products, there are three major components to consider: soil, compost, and mulch. Each of these soil products has different applications, depending on your project.

Topsoil usually refers to the top 2 to 8 inches of ground soil. It is the most productive layer of soil. Topsoil contains some organic matter along with minerals and nutrients. It can be used to top off your plant bed or mixed with rich, organic material.

Compost is decaying plant or animal matter that turns into nutrient-rich soil. You use it as a soil amendment. Gardeners or landscapers can add compost to topsoil or any other soil (garden soil or potting soil) to enrich it with nutrients. It acts as a soil fertilizer as well as allowing for better drainage in clay soils and allows sandy soil to hold onto nutrients.

If you have ever noticed wood chips as an attractive landscaping choice in a front yard, that is a kind of mulch. Other options include shredded yard waste (shredded leaves and grass clippings), straw, and sawdust. Mulch looks nice, and it is suitable for discouraging the spread of weeds and supplies shade to the undergrowth. It covers the soil and helps retain moisture normally lost through evaporation in the summer and provides insulation in the winter.

Look for a Local Source

Once you understand what type of soil products you need, ask the local experts. Talk to gardeners, the specialists at the garden centers, and your local cooperative extension. The cooperative extension will likely be your most productive resource; it is their mission to serve as a community education resource on agriculture and horticulture. Avid gardeners and local hobbyists usually buy in bulk, too. They are going to be your best judge of what is available near you.

Examine the Soil Products Before You Buy

Even if you get a few great recommendations, examine the product before you buy it. Soil companies usually have several blends available, such as topsoil, lawn soil, garden soil, and a compost/soil blend. Some will even allow you to custom-make your mix, such as 40 percent compost with 60 percent topsoil (this might have an extra charge).

For garden soil, a sandy loam is ideal. Look for less than 15 percent clay and at least 5 percent organic matter. It should be dark in color, crumbly, and loose feeling. There should be some moisture, but it should not form a hard ball in your hand.

You can have the soil professionally tested, but it will take time and can cost more than $100. Some companies may offer soil analysis or soil certification.

Good topsoil and compost should have no odor other than a rich, earthy smell. It should be loose and crumbly. Even straight compost should not be coarse or chunky. Freshly made compost may still have some heat, but it shouldn’t be hot.

Soil Characteristics

• Soil pH: Ideally, your topsoil should be somewhere between 5.5 and 7.5. You may need to test this yourself if this information is not listed.
• Organic content: Find out how much compost is in the mix. Ask what the compost made from. Yard and leaf waste is a neutral compost, whereas a manure-based composed can add a lot of nitrogen, which isn’t suitable for all plants.
• Soil texture: Soil is made of sand, clay, silt, and loam and refers to the mineral particle sizes. More than 40 percent of clay can clump your soil and create soil drainage problems. More than 70 percent of sand can make the water feeding your plant run too fast through the soil.
• Screening: Check that the soil runs through a screening process that removes rocks, litter, and clumps of clay.
• Weed-free: Make sure the soil is at least 98 percent weed-free. You do not want soil or compost that sprouts weeds and creates more weeding work.

Determine How Much You Need

Bulk soil, compost, and mulch are sold by the cubic yard. Calculate the cubic yards you’ll need for different planting depths using the depth of soil calculation chart (below):

1. Measure the area or square footage (length x width) of the space to be covered.
2. Decide how deep you want your mulch. Select the number of inches of coverage on the chart.
3. Determine the corresponding square feet/cubic yard.
4. Divide the square footage of your garden by the square feet/cubic yard number.

Example

Calculate the amount of needed soil for a 25-foot-by-20-foot (500 square foot) garden:

1. Your garden has an area of 500 square feet.
2. You want 6 inches of mulch.
3. The corresponding number on the chart for a 6 inches depth is 54.
4. Divide your square footage (500) by 54, which equals 9.26 cubic yards.

In this example, it means you need 9.26 cubic yards of soil or mulch to cover a 500-square-foot garden to a depth of 6 inches.

Calculate Depth of Soil