Mulch provides a lot of benefits in a landscape; it gives an area a tidy, finished look, helps control weeds, and many mulches help retain moisture, protect plant roots, and break down over time to add organic material to the soil. But to achieve the most benefit, you need to apply the proper depth of mulch.
How deep should mulch be?
Too little mulch and areas may look sparse and unfinished. Also, there may be little benefit to plant health if the mulch is too shallow. Too much mulch and water may not get through to the plant roots. In addition to water, plant roots also need air to thrive. Thick layers of mulch can reduce the air supply to a point that it can decrease root growth and cause a plant to decline or even die. So what amount of mulch is “just right”? Ideally mulch should be at least 2” deep, but no more than 4”.
How much mulch do you need?
To know how much mulch you need, first determine the size of your planting space. Measure the length and width of your planting area. Multiply those together and you’ll get your total square feet.
Width in feet x length in feet = total square feet
For a 4’ wide x 6’ long planting area: 4 x 6 = 24 square feet
How many bags of mulch do I need?
Since mulch is often sold in 2-cubic foot bags, here’s a handy guideline for determining how much you need:
1 – 2-cubic-foot bag of mulch will cover 12 square feet, 2 inches deep
1 – 2-cubic-foot bag of mulch will cover 8 square feet, 3 inches deep
Purchase mulch by the bag or bulk delivery?
If you need a large quantity of mulch, it’s often cheaper to buy in bulk by the cubic yard. For cost comparison you should know that it takes 13.5 bags of 2-cubic-foot packaged mulch to equal 1 cubic yard of loose mulch. Even with a delivery charge, buying mulch in bulk can be the best value when dealing with a large area. To determine how much to buy, you need to know how many cubic feet you want to cover. First take the number of square feet that you calculated earlier and put it in this formula:
Multiply your total square feet x the depth of mulch you want/ divided by 12 inches = total cubic feet
24 square feet x 2” layer of mulch = 48”/ divided by 12” = 4 cubic feet of mulch
24 square feet x 3” layer of mulch = 72”/ divided by 12” = 6 cubic feet of mulch
Spring and fall are equally good seasons for applying mulch. Spring applications help hold moisture through the summer and keep roots cool. Fall applications help protect tender or shallow-rooted plants from the freezing temperatures in winter. Either way your plants are sure to benefit and you’ll love the polished, professional appearance mulch adds to the landscape.
Not sure what mulch to choose? Check out our article, “What’s the Best Mulch for My Landscape”, to learn about some of the most popular mulches.