When you have a large area to cover in your landscape, mulch in a bag won't do the job. It's much more cost-effective to order mulch in cubic yards and have it delivered to your property. One cubic yard is equal to 27 cubic feet, or a block of mulch that is 3 feet wide, 3 feet long, and 3 feet high. The area that a cubic yard can cover ultimately depends on the depth of your mulch.
Bags of mulch are typically sold in quantities of just 2 cubic feet. While bagged mulch is easy to handle, doesn't require a delivery fee, and is usually returnable if unused, you would need to buy 14 bags of mulch to cover the same area as a cubic yard.
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One cubic yard of mulch covers 324 square feet at 1 inch deep, 162 square feet at 2 inches deep, or 108 square feet at 3 inches deep.
Determining the Depth of Mulch
In most cases, landscapers recommend spreading mulch at a depth of about 3 inches, but this can vary. Flower beds benefit from a thinner layer of 1 or 2 inches, while trees and shrubs can handle a thicker layer of 3 or 4 inches. (Never mound mulch up against a tree trunk, which invites rot and insects.) Dense mulches, such as very finely shredded bark mulch and sawdust, should be spread at a depth of 2 inches at most, while a fluffy layer of pine straw can be 4 inches deep. The idea is to find a depth that suppresses weeds without smothering the plants and blocking rain from reaching the soil.
Mulch settles, decomposes, and washes away over time. If you are refreshing a mulched bed with a top layer, 1 or 2 inches will likely be enough. When in doubt, a total depth of 3 inches is appropriate for many applications.
Calculating Mulch Coverage
Begin by measuring how much area you need to cover in your landscape. Measure the length and width of each garden bed in feet and multiply those figures to determine square footage. If you have multiple garden beds, you can add the square footage together to determine the total area you want to mulch.
When applied in a 4-inch layer, 1 cubic yard covers 81 square feet. Scattered at a depth of 3 inches, a cubic yard of mulch covers 108 square feet, while a 2-inch layer covers 162 square feet, and a 1-inch layer covers 324 square feet. To determine how much mulch you need, use this formula: total square footage x desired depth / 324 = cubic yards needed.
However, the easiest method for calculating how much mulch you need is to use a mulch calculator. Enter your measurements and desired depth, and the calculator will report how many cubic yards you need to order. Once that load of mulch arrives, it will go a long way in transforming your landscape.