Mulching Mistakes to Avoid

birch tree in mounded mulch

Mulching is an essential practice in gardening that plays a fundamental role in promoting healthy plant growth and boosting yields.

Mulch helps reduce loss of moisture from the soil through evaporation, and can also keep the soil cooler during hot summer months, meaning you won’t have to water as much. It also helps to minimize the growth of weeds, prevents soil compaction, and protects root systems.

Mulching is fairly simple, but there’s an ideal process to follow. Here are some mulching mistakes to avoid.

Mulching Too Much or Too Little

hands mulching small plant

The amount of mulch used is critical for success. If you heap too much onto the soil surface around the plants, it may cause feeder roots to divert to the surface, which will stress the plants during adverse weather conditions.

Too much mulch can cause suffocation of the plant as it hinders oxygen from getting in. Similarly, you want to make sure to add enough mulch, as too little won’t provide any of the benefits.

The recommended amount may vary, but generally speaking, aim for two inches, topping up as needed during the growing season.

Placing Mulch Improperly

Avoid packing mulch right next to the stems or trunks. Allow space around the base of the plants to enable breathing without hindrance.

A common practice when mulching trees is to pile up the mulch at the base of the tree. This is known as volcano mulching. This practice traps moisture against the tree bark and encourages bacterial and fungal diseases, which can severely harm or kill the tree.

Instead, arrange the mulch around the tree base so it resembles a bagel, leaving space for air to flow.

In other areas, spread mulch evenly around garden beds to achieve a well-manicured look, and pay attention to the borders where gardens meet the grass.

mulch around a small tree

Mulching at the Wrong Time

There is such a thing as too early or too late when it comes to mulching. The best time to lay it down is mid-to-late spring when temperatures are consistently above freezing and the soil has had enough time to warm up. This also allows time for the spring rain to do its job.

Many people are tempted to clean up garden beds too soon. While this may look “neat and tidy,” it may injure beneficial insects in the soil that are not yet ready to be disturbed, and plants themselves, which are still coming out of their dormancy period.

Wait until perennials have popped up and matured enough to handle any vigorous weeding and mulching. Clean up and mulch beds around the same time of year to get the best growing success.

There’s no need to mulch into the late fall, as plants begin to go dormant again. The soil doesn't need insulation in fall as it did during the hotter months, though adding some organic material directly after the growing season can be beneficial.

Using the Wrong Mulch

green rubber mulch

Organic mulch (as in organic material, not necessarily organic certified) is by far the best option for gardens with plants.

Inorganic material like rubber, stone, or brick pieces can help suppress weeds in an area where you don’t want anything to sprout, like a walkway, playground, or hardscape garden.

The most common organic mulch used is the commercial bags sold at garden centers and hardware stores. These usually come in black, red, and various shades of brown, and are cheap by-products from lumber companies.

The dyes aren’t great for your soil, and buyer beware, they tend to fade after just one year. They will do the job, but higher quality organic material is recommended. Shop around at local nurseries, or call eco-friendly landscaping companies to see where they get their supply.

Local municipalities will often give away mulch made from ground Christmas trees that were picked up months before. While it’s usually free, and made of organic material, this kind of “green” mulch will steal much-needed nitrogen from the soil as it decomposes.

Better to use your own green mulch that has aged and dried over the winter like your garden clean-up. Dead leaves, foliage, branches, straws, and stems can all be chopped up and distributed around your beds.

It’s not as decorative as the commercial bags, but your plants will be much better off, and the soil will benefit from the nutrients. This is one of the major rules of permaculture planting—use spent material to help the new yield grow.

Check the Source

Be aware of where you are buying your mulch before you apply it. Confirm with your supplier where the mulch originated and what's in it.

Some mulch may contain dangerous materials and elements such as metals, plastics, toxic substances, and other harmful contaminants. Make sure you obtain mulch that is certified as safe and reliable from your supplier.

While commercially sold bags are generally safe (even with a certain amount of dye), old bags left around over the year often become moldy, so check before you purchase.

Same applies to any stored mulch over the winter—make sure it’s been aerated enough and has maintained its quality.

Freshly laid mulch gives your garden a clean, unified look once it's filled in the gaps between plants, while also providing many benefits for them.

While there are a few options for what kind of mulch to use, try to find good quality, organic mulch that will last more than a season.

As long as you lay your mulch at an appropriate time, pay attention to the consistency, and use quality products, you can avoid any major mulching mistakes.