How to Install Mulch When Edging a Bed
Edging gives definition to garden borders, and helps to prevent weeds and grass from spreading into undesired areas of the garden, but mulch adds the finishing touch to give flower beds a neat appearance. The border edging can be as simple as a shallow trench, or a row of stones or bricks. Flower beds generally require a 2- to 3-inch mulch layer for best weed suppression, but adding this depth directly against the edging can allow grass or weeds to cross over the edging and take root in the mulch.
Calculate the number of cubic yards needed to cover the area with the desired depth of mulch, usually 2 to 3 inches of mulch form flower beds, and up to 6 inches for large trees. First, multiply the length of the bed times the width to determine the area; for circular flower beds, multiply the diameter times 3.14 to find the area. Next, multiply the area times the desired mulch depth to find the number of cubic yards needed. For example, a 10-by-10-foot flower bed has an area of 100 square feet. To cover the bed with 3 inches of mulch, multiply 100 times 0.25, because 3 inches is one-fourth of 1 foot, and you'll get a figure of 25 cubic yards of mulch.
Spread the mulch evenly over the flower bed to cover the area with the desired depth of mulch, leaving about 6 inches in from the edging free of mulch. Leave a few inches around each plant base free of mulch to avoid rotting the plant stems.
Drag the mulch from the top of the flower bed down to the edging at an angle. The mulch should form a 45-degree angled diagonal line beginning from the top of the flower bed mulch down to the bottom of the trench, stone or brick edging.
Pack the mulch gently so it stays in place while still allowing water to pass easily through the mulch material to the soil.
Reapply mulch as needed to maintain the desired depth as the mulch decomposes. This is only necessary for organic mulch materials. Inorganic materials, such as gravel, do not decompose, but you may need to redistribute the gravel if it washes out from heavy rain or watering.
- The exception to this mulching method is polyvinyl landscape edging in which mulch generally is applied straight across so only the round top edge of the edging remains visible above ground.
- In addition to the standard wood mulches, you can use finished compost, manure, straw, newspaper, lava rock and grass clippings as mulch. Only use grass clippings from lawns that haven't been treated with pesticides and herbicides, and from grass that hasn't gone to seed or the grass seeds can sprout up in your flower beds.
A former cake decorator and competitive horticulturist, Amelia Allonsy is most at home in the kitchen or with her hands in the dirt. She received her Bachelor's degree from West Virginia University. Her work has been published in the San Francisco Chronicle and on other websites.