Rock Mulch vs. Bark Mulch – Which is Better for Gardens?

Author: Touré Foster

Posted in: Landscaping

Rock Mulch vs. Bark Mulch - Which is Better for Gardens?

If you take a ride through a residential neighborhood, you’re bound to see gardens. Some will have rock mulch and some will have bark mulch. It begs the question, which is better? While both alternatives are functional and visually pleasing, the best option comes down to what works best for you and the soil.


Bark mulch is an environmentally friendly option. A two-inch layer of bark mulch cuts water usage in a garden by 20 percent because it retains water. Rock mulch won’t hold any water and they retain heat making the garden temperature higher. So, if you’re looking for an option where you don’t spend your time watering, bark mulch is your best bet.

Initial Cost

Bark mulch is much less expensive than rocks. At less than a dollar per square foot, bark mulch is a better option if you’re on a budget. Rocks can cost anywhere between one dollar and fifty cents to three dollars.


Anyone can put down bark mulch. All you need is time and some simple gardening tools like a rake and/or shovel.

Rocks, on the other hand, can get heavy so you may need to hire a contractor with machinery to help you.


If you’re looking for something different, more of a variety, rock mulch is the best option. They come in different colors, shapes and sizes. You can use lava rock, quartz, granite, pea gravel and river rock. And the sizes can range from the size of a grape to the size of a golf ball.

Bark mulch has a typical shape and size. And bark mulch color is limited to three options: brown, black or red. If you want your landscape areas to look like well-behaved dirt, brown mulch is your best option.

Cost over Time

While rocks initially cost more, they are a one-time expense. Bark mulch must be replaced every year or two. So, if you’re looking to save money in the long run, rock mulch will help.


As discussed above, anyone with time and simple gardening tools can install bark mulch. But time is the key. Bark mulch’s color will fade over time due to sun exposure. As a result, some people choose to replace it every spring and fall. That’s a lot of time spent spreading mulch. Whereas once rocks are installed, they’re somewhat maintenance-free.

Pros of Using Bark MulchPros of Using Rock Mulch
Requires less wateringMore variety
Less initial costDecreased costs over time
Easy installationMaintenance-free

The pros and cons outlined above boil down to what works best for you: your time, your money, your tools, your preferences. But what works best for the soil? Might this be a deciding factor? Bark mulch is better for the soil because it provides nutrients, eliminates most weeds, and helps flowers thrive.

Nutrients. Because mulch is made of bark, when it decomposes it adds nutrients to the soil. Rocks don’t provide this benefit. 

Weeds. When using mulch, it acts as a natural weed barrier as it blocks access to sun and most weeds will not be able to push through. On the other hand, rocks require a fabric weed barrier. Without this weed barrier, weeds will spring up and take away nutrients from your soil and plants. Plus removing weeds from the rock mulch is more difficult. Using a weed killer works, but that isn’t very environmentally friendly.

Flowers. Since mulch moderates temperature and retains water, it helps flowers grow. Rocks, however, keep the area too warm and as a result flowers won’t thrive in gardens alongside rocks.

At the end of the day, you should choose the option that works best for you. Get in touch with an expert to help you make the best decision for you.