Bark Mulch vs. Rock Mulch: Which is Better?

Do you need to spruce up your yard? Thinking of putting in some ornamental shrubs and edging the flower beds? Adding bark mulch or rock mulch cover to your landscape is a quick and easy way to beautify your yard and garden, but it also provides a lot of other benefits. It protects plants and shrubs, conserves moisture so you don’t have to water as much, slows erosion, and the bark mulch adds nutrients and organic materials to the soil.

wood mulch chips

Where to Use Mulch

There are almost limitless uses for mulch in the landscape, including with patio construction and design, around a fire pit installation, with swimming pool installation, and for many other residential landscaping services. A mulch cover in the fall for winter protection is recommended for many ornamental landscape plants to protect roots and shrubbery from freezing temperatures and drying winds.

Use mulch in flower beds and around ornamental plantings as an attractive backdrop, to keep weeds out, and protect roots from drying out by conserving moisture and providing shade. Don’t confuse compost with mulch. Compost can be used as a top dressing but is normally worked into the soil to add nutrients and organic matter, while mulch is applied on the surface of the soil for protection and beautification.

Types of Mulch

While there are many different materials to mulch with, two of the most common types used for landscaping design are mulch made from tree materials like shredded bark and rock mulch or yard rocks. They are both beautiful and versatile materials, and they both have different benefits and drawbacks.

Bark Mulch

wood mulching project
One of the most commonly used and inexpensive types of mulch is made from shredding the bark of trees. Hardwood bark mulch is a dark brown color but can be dyed red or black. Bark mulch is usually finely-shredded and has an earthy odor to it, especially when it is fresh and first applied on the landscape.

Different Types of Bark Mulch

Many different trees can be used to make mulch. Trees commonly used for much by shredding their bark include cedar, cypress, pine, hemlock, eucalyptus, and oak.

Bark Mulch Benefits

Two of the biggest benefits of using bark mulch include the price and ease of use. Bark mulch is economical to buy at .70 cents to .80 cents per square foot and easy to handle. It can be applied by hand, with a shovel or garden fork, and is commonly available in plastic bags that aren’t too heavy for one person to move. It’s a material that acts as a weed barrier and conserves moisture and shades roots so plants are protected and you don’t have to water as often. It is used as an edging material and a top dressing for decorative garden beds and ornamental plantings. It’s a soft material in the landscape, and adds organic matter to the soil as it breaks down.

Bark Mulch Drawbacks

There are a few reasons bark mulch might not be right for your mulching needs. It has to be replaced every couple of years because it decomposes. The vibrant color that bark mulch has when it’s new will fade in direct sunlight over time, and may not look the same after six months. It can wash or blow away in areas exposed to flood or open winds.

Rock Mulch

Rock mulch is decorative gravel or rocks ranging in size from pea-size to golf ball size. Rock mulch is often sourced from river beds. The price varies depending on where the rock came from, but generally costs between $1.50 to $3.00 per square foot.

Different Types of Yard Rock

yard rock

There are many different types of rock to use as mulch. Rock mulch is heavier to handle and apply than bark mulch. It’s also a more permanent landscape installation, not decomposing into the soil or adding organic matter.

Rock Mulch – Benefits

There are many good reasons for using rock mulch in the landscape. It’s a material that doesn’t decompose into the soil and does not require regular replacement, so it can be more economical than bark mulch. It’s available in a wide variety of colors, shapes, sizes, and textures.

Rock Mulch – Drawbacks

Rock mulch may not be the best material in areas where there is a lot of leaf drop and plant debris that will cover and accumulate on top of the rock layer. It is more expensive up front and heavy, making it more difficult and expensive to install. It requires a weed barrier underneath to keep weeds from growing up through the rock layer and an edging material to keep it out of surrounding lawn.

Once a weed barrier and rock mulch are installed, it can be difficult to add or replace plants later.

granite rock mulch

Quarries may not carry the type of gravel over time, making it difficult to match if you want add more mulch later. Rocks absorb sunlight on hot, sunny days and heat up the soil underneath a well as reflecting sunlight up into the plants above.

Rock mulch can get very warm on hot, sunny days.  You have to be careful with the plants and shrubs with rock mulch cover.

Which is Better? Rock vs. Wood Mulch

Which type of landscaping mulch is better to use, bark mulch or rock mulch, depends on a few important factors, including overall landscape design, budget, and the types of plants and shrubs, if any, the mulch will surround. Homeowners who require snow removal services may have to repair or replace mulch installations close to driveways and sidewalks because of snowplow damage.

Shredded bark mulches are generally better to use in garden beds and to protect ornamental plantings and rock mulches are good to use around building foundations and alongside driveways and walkways. Marianne Ophardt, Washington State University Extension faculty, recommends bark mulch over rock mulch around plants and shrubs because of the way rock heats up the soil underneath it and the temperatures around the plants, stressing and damaging them. She also points out that rock mulch has a tendency to get covered with windblown debris and soil, which gives weeds cover to sprout, and ruins the appearance of the landscape design.