Tips for mulching landscape

Mulch provides many benefits besides visually differentiating planting beds from lawn.

My daughter clung to a blanket until she was 7 years old. By the time she gave it up, it appeared to be a frayed fire hazard. Blankets are normally used as insulators or decoration, much like mulch is used in the landscape. It’s no coincidence both are called beds.

Mulch, however, does much more than a bedsheet. It distinguishes flowing bed lines and keeps lawn mowers from banging into tree trunks. It protects the roots by insulating the bare soil from temperature fluctuations and conserves soil moisture by limiting evaporation. It enriches the soil as it decomposes.

Most mulch materials should be 3 inches deep and pulled 6 inches away from tree trunks and buildings. When mulch is too thick, tree roots can deprived of oxygen. When piled against buildings, it can provide a conduit for termites to invade.

Bags of mulch are most convenient for small beds, but it is more economical to purchase in bulk from local wholesalers. A full-size, half-ton pickup truck can carry about 2 cubic yards. Of course, delivery can be arranged for larger loads.

One cubic yard of mulch will cover roughly 100 square feet with a 3-inch layer. This is approximately a 10-foot by 10-foot area. To estimate your mulching needs, calculate the total square footage of bed space by breaking the area into rectangles. Length multiplied by width of each rectangle equals square feet.

The total square footage divided by 100 will estimate the number of cubic yards needed to spread 3 inches of mulch. This will be adequate for mulching the soil in new beds. If a couple of inches of old mulch are still in place, you may only need a third of the estimated amount.

Keep in mind, if you’re refreshing mulch just to add color to old faded beds, a mulch colorant can be sprayed to avoid over-mulching at much less the cost and effort.

Chopped or shredded wood mulch comes in various colors and types. Cypress or cedar mulch is more expensive but decomposes slower and needs replenishing less often. Hardwood and pine mulch are more economical but break down faster.

Dyed mulches have been a popular homeowner choice for several years. Brown dye has a natural appeal. Red dye is not a natural color but seems to be more popular with some homeowners.

Bark nugget mulch doesn’t seem to be as available as it once was. It can still be found in bags, but bulk availability has become less common. It has nice textural appeal and larger chunks decompose slowly. Bark mulch, however, floats and heavy rain can move it somewhere else. Avoid using on slopes.

Pine straw is popular in the South because it’s readily abundant. If pine trees are near your beds, don’t fight nature with a different type of mulch, just supplement with pine straw as needed.

A study at the University of Florida concluded pine straw has an acidifying effect compared to other mulches, so occasional pH testing may be advisable if plants are struggling.

Pine straw holds slopes fairly well and it’s easy for homeowners to purchase and distribute. For new beds, one bale covers about 30 square feet. It is a bit more airy than wood and bark but will settle down to a 3-inch depth. It breaks down quickly, so plan on adding it every year. Longleaf pine straw is more expensive but generally more visually appealing with slower decomposition rates than short needle.

Inorganic mulch is not as common in the Lowcountry as it is in other parts of the country. It does not need to be replaced. However, because it doesn’t decompose, it will not benefit the soil. Lava rocks, white rocks and pea gravel are all examples. Recycled rubber can be chipped into mini-nuggets that, believe it or not, looks quite natural, but it’s hard to find and very expensive. There’s even synthetic pine straw that doesn’t need to be replaced. That’s right, fake pine straw.

Tony Bertauski is a horticulture instructor at Trident Technical College. To give feedback, e-mail him at tony.