How Many Cubic Yards of Mulch Do I Need?

Mulch is a lawn and garden cover that helps the soil retain moisture, reduces erosion, protects seedlings, provides some nutrients, and prevents weed seeds from germinating. It performs the same function as leaf cover found in forests, protecting plant roots from freezing during the cold. There are mulches made from organic materials, such as wood chips, shredded corn cob, and pine needles. But mulch can also be made from recycled rubber tires, plastic, and crushed stone.

Mulch is distinct from compost; compost is primarily a fertilizer that is meant to decompose and be absorbed into the soil, whereas mulch is primarily a protective layer that may or may not deliver macro and micronutrients. However, compost may be used as both a mulching agent and fertilizer. If using compost as a cover, gardeners must make sure the material is fully decomposed and contains no errant weed seeds.

Gardening supply centers sell mulch by the cubic yard. To determine the volume of covering material needed for your landscaping project, you must consider the area of your garden and the depth of mulch to be applied. If A is the area of your garden in square feet, and D is the depth of the mulch in inches, then the number of cubic yards is given by the formula

Cu. Yd. = (AD)/324

You can also use the calculator on the left, or use the area formulas below to help you compute the cubic yards of mulch needed.

What Type of Mulch Do I Need and How Much?

The type of mulch you apply is a matter of preference. Organic materials such as wood chips, pine needles, and compost can alter the pH of your soil for better or for worse. You can also mix different products. The depth of mulch depends on the material and season. If the mixture is finely shredded, you can apply 2 to 4 inches during the warmer seasons. To protect your plants during the winter, prune the plants and cover the whole bed with about 6 to 8 inches of mulch.

Area Formulas

Rectangle: Area = LW, where L = length and W = width
Triangle: Area = (0.5)BH, where B = base and H = height
Triangle: Area = (0.5)sqrt(2C²D² + 2C²E² + 2D²E² - C⁴ - D⁴ - E⁴),
             where C, D, E are side lengths
Circle: Area = (3.14159)R², where R = radius
Semi-Circle: Area = (1.57079)R², where R = radius
Quarter Circle: Area = (0.7854)R², where R = radius
Ellipse: Area = (0.7854)XY, where X = length and Y = width

Remember, the radius is equal to half of the diameter.

© Had2Know 2010