Mulch is a smart addition to any garden. Preventing weeds and creating a beautiful base, it will help you keep the garden gorgeous throughout the growing season. It also serves a valuable purpose in the winter by protecting tender plants and preventing weeds in the early spring. The question isn’t whether you should use mulch, it’s how much mulch you need. Fortunately, there is a mulch calculator formula you can use to answer this question.
Know Your Purpose
There are different reasons to mulch a bed. Maybe you are filling an area where you don’t want anything to grow. Perhaps you are using it to protect young plants over the winter. Most likely, you want an attractive covering that will block most weeds.
If you are applying mulch between plants to prevent weeds, you should use three to four inches if your mulch is coarse. If you are using finer mulch, then you will only need one to two inches. Keep it away from the base of plants that are growing, and try not to put it up under leaves where it might smother the roots. One cubic yard will cover 100 square feet if applied at three inches deep, but you can get 160 square feet of coverage if you are only spreading it to a two-inch depth.
Where Nothing Will Grow
There are areas where you don’t want anything to grow, like around your pool or your air conditioning compressor. Start by putting a layer of newspaper down in these areas, and then cover them with four inches or more of mulch. Your cubic yard of mulch will only cover about 90 square feet, but you won’t have to spend as much time pulling weeds, grass and other plants.
If you are using mulch to protect tender young roses or azaleas, then you will need a heavy layer to serve as insulation. Wait until after the first hard freeze for the plant to go dormant. Then apply a thick layer of three to four inches around the base of the plant. Remember to remove the mulch and spread it over the surrounding area as soon as the threat of freezing temperatures in the spring passes.
While buying in bulk will certainly save you money, it’s a waste if you are only covering a small area. Most bags contain two cubic feet, and that will cover roughly eight square feet at a depth of three inches. A full yard of mulch will cover a larger area of about 100 square feet at three inches in depth.
Determining Square Footage
A mulch calculator formula
is surprisingly simple. Start by multiplying the length of your bed by the width. Circular beds should be measured by first finding the radius, or the distance from the outside edge to the center. Multiply the radius by itself and then by pi, or 3.14. Your formula would then be r * r * 3.14. If you have beds with odd shapes, then draw them out on graph paper and divide them into manageable areas to determine the square footage. An L-shaped bed is easier to measure if you break it into a rectangle and square, and kidney shaped beds can be broken into two slightly overlapping circles.