Discover the Importance of Mulching: Mulching 101

Covering soil with mulch is one of the most widely discussed topics in gardening and landscaping.

Mulching can be great for your garden soil, help suppress weeds, and make your yard look amazing. It can transform an outdoor space into a beautiful haven and is essential for an orchard.

Yet, I still see many gardeners making mistakes with mulch. In this post, I share what I wish I had known as a beginning gardener: the importance of covering soil, types of mulch, the best way to use mulch, and common mulching mistakes to avoid.

Grow Big or Go Home

If you want to “Grow Big or Go Home,” you cannot neglect your soil! Healthy soil is the foundation of a thriving, productive garden.

To keep soil healthy, you need to apply compost or vermicompost regularly, apply mulch, and use soil amendments to remineralize each growing season. In the years I've been gardening, I’ve learned so much about how mulching helps the soil, and I want to pass that on to you.

Why Is Mulching Important

Mulching is simply the practice of covering soil with a layer of material. But why is that important? What is the real purpose of mulching?

Mulch is intended to protect the soil quality by creating an insulated barrier. If you are not mulching your soil in some way, shape, or form, then you are doing your soil a disservice.

Many people consider soil boring: only sand, silt, and clay. But soil is a living thing bursting with flora and fauna. Bacteria and fungi are incredible miners of minerals that soften and loosen the soil and unlock nutrients to feed your plants. The bacteria and fungi in soil account for up to 70% of the nitrogen plants use.

If soil microbes and bacteria in the rhizosphere are not protected, they will die in extreme weather. That is where mulching comes in. Mulching provides that vital insulation to protect living soil during winter freezes and summer heat alike!

Essential Benefits of Mulching Your Garden

In addition to protecting the rhizosphere and improving soil quality, mulch conserves moisture in the soil, meaning you will need to water less often. As it breaks down, mulch will add more organic material to the soil.

Mulching helps to keep the soil cooler. Whether you are growing trees and shrubs, ornamental plants, or garden plants like tomatoes and peppers, a cool plant is likely a healthy, stress-free plant.

Mulch can keep the soil up to 20 degrees cooler than the ambient temperature on a hot summer day. Exposed soil is susceptible to soil solarization, which can kill beneficial microbes and organisms. Mulch is like nature’s sunscreen for your soil.

It makes your garden look good and stay healthy with less work.

Different Types of Mulch Materials

There are many different types of mulch and many terms being thrown around. Let’s define some terms so we are on the same page regarding mulching.

• Organic Mulch - Plant materials can make great mulch. Organic mulches include leaves, wood mulch, pine needles, semi-finished compost, grass clippings, and straw.

• Living Mulch - Living mulch is a crop that grows up but isn’t harvested, instead letting it remain to cover and protect your soil. Cover crops, like clover, are a living mulch.

• Inorganic Mulch - Inorganic mulch is made from non-living materials like rock, rubber, or plastic.

Pro-Tip: When I talk about wood mulch, I am specifically talking about organic mulch made from shredded wood. It may contain some bark and leaves but not large wood chips. Wood chips are larger pieces of wood that take longer to break down. They are usually used decoratively, while wood mulch is used for soil health.

Here are some common types of mulch materials:

Potential Mulching Mistakes

When I started gardening years ago, I made all these mulching mistakes and more. I hope you learn from my mistakes so that you don’t have to learn the hard way. 

• Mulch Is Too Deep - Mulch that is too deep can cause many problems. It creates an area for mice and other pests to live, and it holds a lot of moisture, causing problems like trunk rot in fruit trees, damping off, and root rot.

• Mulching Too Close to Tree Trunks - Retaining moisture near tree trunks by mulching too close causes mold, mildew, and rot. Also, it invites critters, like mice, to come close and eat away the bark of the tree.

• Using Dyed Mulch - Natural is better! Natural mulch contains no artificial dyes or coloring agents. Those chemicals will leach into the soil and, over time, really hurt soil microbiology and soil fungi. They can even be absorbed into the plant, so avoid dyed mulch around any edibles.

• Using Rubber Mulch - I am all for recycling and reducing waste. At first glance, rubber mulch might seem like a good choice because it is usually made from old tires. However, the heavy metals, microplastics, and other toxins in tires are incredibly damaging to soil health and overall plant health! Not to mention, those contaminants will stay in your soil. They take thousands of years to break down.

• Mixing Mulch into the Soil - Mulch should sit on top of the soil and never, under any circumstances, should it be turned or rototilled into the soil! Raw mulch (uncomposted) will damage soil and plant health when mixed into the soil because of nitrogen sequestration (the process where bacteria use up the available nitrogen to break down uncomposted organic matter).

• Putting Organic Mulch Right Next to Your House - Shotgun Fungus (also called Bird’s Nest Fungus and Artillery Fungus) loves to live in organic mulch. This type of fungus spreads its spores through an explosion. They shoot their spores up to 15 feet and will pepper your house, siding, windows, and cars with these tarry black spots that are nearly impossible to remove. It can cause $1,000s worth of damage.

• Not Using Mulch - Another big mistake I see gardeners make is choosing not to use mulch. Don’t neglect the health of your soil and miss out on all the essential benefits of mulching!

• Paying Too Much for Mulch - I like to use living mulch and whatever organic mulch I have on hand because it is inexpensive. When I need wood mulch, I look for a tree service company that will deliver it for free. Pro-Tip: ChipDrop can help you find cheap, local mulch.

Calculating the Right Amount of Mulch

Here is a simple calculation to determine how much mulch you need:

1. Calculate the Surface Area - Measure the surface area that you will be covering with mulch (for example, a garden bed's length x width). Pro-Tip: If you are planting living mulch or using plastic sheet mulch, the surface area is all you need to calculate. Skip steps 2 and 3.

2. Depth - Decide how deep you want the mulch across that area (I usually plan on about 3 inches of depth when using organic mulch).

3. Calculate - Multiply the depth x the surface area.

Let’s say I want to cover an 8-foot x 4-foot garden bed with 3 inches of organic mulch. First, I would multiply 8 x 4 to find that the surface area of my garden bed is 32 sq. feet. Using the same unit of measure (feet), I want the mulch to be ¼ foot deep (3 inches). Then, I would multiply 32 x ¼ to find that I need eight cubic feet of mulch to cover that garden bed.

Applying Mulch Correctly

1. Source Quality Mulch - Choose the type of mulch that best suits your needs and ensure you have enough for your project.

2. Dump Mulch - Dump the mulch into your garden area.

3. Spread - Using a hard rake, spread the mulch evenly over the entire area to achieve the desired depth. Do not mix the mulch into the soil!

4. Move Away From Tree Trunks - Pull the mulch away from trunks and plant stems to protect them from rot.

Mulching is not a one-time job. It's a regular part of gardening. I do not want you to neglect your soil; instead, I hope this helps you make fewer mulching mistakes in your garden and orchard.