Mulching Mistakes to Avoid: Common Errors and How to Fix Them

Mulch provides a whole slew of benefits to your landscaping: water conservation, temperature regulation, weed suppression, soil health, and erosion protection, among other things. But like everything else, too much of a good thing can be a bad thing.

Here are some common mulching mistakes homeowners make and how to avoid or fix them going forward.

It’s Just Too Mulch

Because mulch has so many benefits, many people are under the impression that you can never have too much–but that’s not the case. When you over-mulch, you suffocate the roots, delay dormancy, waterlog the soil, create excess heat, and provide a hiding place for pests. It also causes plant roots to decay faster.

Mulch is great for water conservation because it’s thick and retains moisture, but too much thickness and moisture can have adverse effects. Too much mulch can reduce the amount of oxygen in the soil, slow evaporation, and increase heat, which suffocates the roots, waterlogs the soil and root zones, or burns the plant roots.

Essentially, the right amount of mulch can improve every aspect of plant growth, and too much mulch can destroy everything. As a good rule of thumb, you only need about a 2-inch layer of mulch, and you don’t want to lay it too close to stems or tree roots.

Using the Wrong Type of Mulch

Luckily, when it comes to choosing your mulch type, it’s hard to go wrong. Ultimately, to protect your garden and soil, you want to look for organic, hand-sorted, locally sourced mulch. There are two types of mulch: organic and inorganic. Organic mulch is made of natural or plant materials, while inorganic mulch is man-made. The one you choose depends on your landscaping goals. Inorganic mulch tends to last longer than organic mulch, deters pests, and suppresses weeds. It’s mainly used for a decorative touch as it doesn’t improve soil or plant health. Organic mulch, on the other hand, is made to improve soil structure, add nutrients, and suppress weeds, among other benefits. It may need to be replaced more often, but you can make organic mulch yourself. Overall, it depends on whether your goal is healthier plants or an aesthetic improvement. You want to avoid four types of mulch at all costs: cheap mulch, mulch with fine particles, allelopathic mulch, and dyed mulch. Cheap mulch will decompose quickly and negatively affect your soil’s pH. Fine mulch can compact and prevent water infiltration. Alleopathic mulch releases chemicals that inhibit plant growth. Dyed mulch may contain colorants that are toxic to pets, children, and beneficial soil microbes.

Applying Mulch Too Close to Stems

When mulch is applied too close to a plant’s stem, it can cause a number of problems, such as root girdling, decay, pests and rodents, reduced gas exchange, and temperature issues. This is a particularly common problem with trees.

When roots grow into the mulch and wrap the stem, it can kill the plant. The moist environment created by mulch against the stem can make the stem susceptible to rot and disease. Mulch can also attract rodents and pests that may harm a plant.

The tissues at the base of a tree trunk have pores called lenticels that they use to “breathe,” but mulch can reduce the necessary gas exchange when applied too close to the stem. Additionally, when applied too close to the stem, mulch can keep plants too hot in the fall, delaying dormancy or too cool in the spring, preventing dormancy from breaking.

Good practice is to apply mulch 3-5 inches away from the stems of young plants and shrubs and 8-12 inches away from mature tree trunks. You can extend it out to a tree’s drip line.