In last month’s article “Mysteries of Mulch Unearthed” readers discovered the benefits of mulch, the various types of mulch and tips detailing the pros and cons when used in varying landscape scenarios.

Today’s article is part two in this series expounding further on “mulching” practices to avoid and taking a closer look at a few mysterious organisms one may encounter in mulch while strolling around the landscape.

If you haven’t already, now is the time to add a fresh layer of mulch. Before topping your beds, it’s helpful first to measure the depth of the mulch already present. A 2- to 4-inch layer works well and provides many benefits to plants such as weed suppression, moisture retention, the slow addition of organic matter and protection from weed-eater and lawn mower damage around trees and shrubs.

Since mulch has so many benefits, it’s easy to conclude more is better. In reality, when the depth of mulch builds up to 4 inches or more it often becomes hydrophobic, or water repellent. When this happens water simply runs off the top of the mulch rather than soaking into the soil, leaving plants thirsty.

Another concern is air when applying too much mulch. Normally, individuals fail to consider the role of air in the soil, but roots need air to survive. Burying root systems under excessive layers of mulch reduces the amount of air in the soil, causing plants to decline and die a slow death from over-mulching.

Another common mistake is to treat mulch like a soil amendment. While products such as compost or finely ground pine bark tend to break down into small particles, most mulches are too coarse to be utilized as a soil amendment. This is particularly true of hardwood mulches, pine straw and pine nuggets. If you determine your mulch has become mixed with soil, dig down until you reach pure soil in which to plant. Often mulch and soil are mixed together by accident when new plants are set out. To avoid mixing mulch with soil, rake down to the soil level and be sure to plant into the soil rather than mulch.

When working with mulch, it’s interesting to know that both soil and mulch teem with millions of living microorganisms such as beneficial fungi and bacteria that work to break down organic matter and release nutrients in the soil. At times, some of these unusual organisms catch a homeowner’s attention causing them to wonder about their identity.

On one such occasion, while walking along your property, you may come across a very distinct odor as if something has died in or around the shrubs. The culprit behind this smelly situation may be the fungus known as the octopus stinkhorn, or dead man’s fingers. This small mushroom is not damaging to plants, people or pets, though the smell can be quite foul and unpleasant. Octopus stinkhorn appears during mild, damp weather and is one of several types of mysterious fungi that occasionally grow in hardwood mulch or wood chips.

Another unusual eye-catching slime mold commonly referred to as dog vomit is a mat-like growth that begins as a small area a few inches across but can quickly grow up to 3 feet in diameter. Dog vomit may range from bright yellow or orange, fading to brown and tan as it dries. Slime molds, although unsightly, do not harm plants and usually dry up within a few days of forming. Slime molds are more common in the springtime but can be observed throughout the summer too. If their appearance is offensive, they can be scooped up and added to the compost or thrown away.

Other types of fungi can be interesting and diverse in looks as in the case of the bird’s nest fungus. Bird’s nest commonly grows on hardwood mulch in fall and winter and looks like a miniature nest containing several tiny eggs. This fungus is brown or grey in color and only one-quarter inch across so it’s commonly overlooked. Another noticeable group are the earth stars. Earth stars pop up out of the mulch, are brown or tan in color, and resemble a button mushroom surrounded by a star shaped halo. Earth stars are common on hardwood bark mulches and wood chips.

Most of the molds and fungi commonly observed in mulch are harmless and although some are a nuisance, there is little that can be done other than waiting over the course of time for the growth to disappear.

Christine Bredenkamp is NCSU horticulture extension agent for Swain and Jackson counties.