Rock Vs. Mulch: Best Landscaping Uses for Each

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Rock mulch with flowers growing out of them.

When you’re planning out new landscaped beds or hardscape features, you’ve got a choice to make: Rock or mulch?

Rock mulch is classified as inorganic, meaning that it will not decompose. The benefits of rock mulch include less maintenance, lower cost over time and not washing away in flood-prone areas.

Standard mulch is most often made from chipped or shredded wood, and it is an organic material that will decompose over time. The benefits of mulch include a lower initial cost, a natural look and use in vegetable gardens and annual flower beds.

While organic materials often win the competition of rock vs mulch in everyday life, there are many times when using rock instead of mulch is a good or even better alternative.

In this post, you’ll learn more about where rock mulch can most benefit your landscape and garden needs. We’ll also cover a few instances of where you’re better off sticking with chipped/shredded wood or another organic material.

Let’s jump in!

RELATED: We’ve put more mulch suggestions for various types of garden and landscape beds in our Mulch Mastery guide. Stop on by for more details!

Types of Rock Mulch

There are few sizes and textures of stones that fall under the category of rock mulch. Here are the most common ones:

  • Crushed stone (gravel)
  • Pebbles (also called pea gravel)
  • Lava rocks
  • River rocks
  • Marble chips
  • Slate

Many types of rock mulch come in shades of grays and browns, which provides a neutral, subtle backdrop to many plants and landscape features.

But with red lava rocks, black slate and bright-white marble chips, you can also use stones to create a vibrant accent section or all-over color.

Types of Standard Mulch

As we mentioned briefly before, standard mulch is made from organic materials that will eventually break down. The most common material for standard mulch is shredded or chipped wood, typically from these sources:

There are also other organic materials used for mulch, including cocoa bean hulls and pine straw, which is made from fallen pine needles.

When to Use Rock Mulch

With their sturdy nature and heavy weight, rocks can be a great solution for several landscape challenges. Here are the times when stone mulch is a great fit:

  1. You want a lower long-term cost
  2. You want a low-maintenance landscape
  3. Landscaping areas prone to standing water
  4. Bordering established trees and shrubs
  5. Creating drought-resistant plantings
  6. Bordering your hardscape
A rock mulch bed bordering a building.

Let’s look at each one in more detail:

1. You Want a Lower Long-Term Cost

Standard mulch materials were once living and will decompose back into their basic natural elements over the course of time. This means that you’ll have to add a fresh layer of mulch as least once a year to keep your landscape looking fresh, or completely remove the faded mulch and replace it with new every 2 years or so.

No surprise here, but this can get expensive.

Rocks will not break down by any significant degree, even over the course of several years. Most types of rock mulch should last at least 5 years, and many times that can easily stretch to 10 years.

While rock mulch does cost more to purchase at the outset, its long lifespan spreads that cost over time, costing you less in the long run.

2. You Want a Low-Maintenance Landscape

We already established that rock mulch costs less money due to its durable nature. But you can also save a lot of labor by using rocks instead of mulch.

Stones of all kinds tend to stay put better than feather-light wood chips that can get blown or washed out of place. Also, I’ve had to clean up more times than I care to recall after small animals dug in my wood mulch.

With the proper initial precautions and a commitment to minimal upkeep, you can look forward to years of beauty from your landscape rocks. Here are a couple of tips for maintaining stone mulch:

Use a weed barrier. As opposed to wood mulch, rocks have more nooks and crannies for weeds to find their way through. See how this rock mulch bed has some pesky weeds popping up?

Weeds peeking through a layer of stone mulch.

Prevention is the best strategy to keep weedy ugliness from invading your landscape. 

Before laying the first rock, cover the bare soil in your landscape bed with a physical weed barrier. A couple of good barrier options include garden fabric or black plastic.

These materials block sunlight to prevent any existing weed seeds from germinating. Additionally, these barriers keep new weed seeds from reaching the soil. 

Clean stones periodically. Wind will likely blow dust and dirt onto your landscape rocks over time. If left unattended, weeds may take root in this top layer of dirt. 

Make washing your rock mulch a part of your spring and fall home maintenance routine.

Although washing rocks sounds like a tedious task, it really isn’t. Spraying your rocks off with a hose should be enough to keep stones fresh and weed-free. This high-power nozzle is a great choice for standard garden hoses.

Use a leaf blower on an appropriate setting. Leaves and other debris find their way into landscape beds annoyingly often, whether you mulch with rock or anything else. But thanks to their heavier weight, a leaf blower gets stone mulched beds clear faster and easier.

Just be sure to use the correct power setting for your type of rock. Smaller, lighter stones, like gravel or lava rocks, can get blown away pretty easily, so use a lower setting on your blower. River rocks can withstand a higher airspeed, so feel free to fire your blower up to full power.

RELATED: Stop by our post on inexpensive cordless leaf blowers to see some great options that cost less than $100. And if you’re looking for greater performance, look over our list of high-powered leaf blowers to get some ideas.

3. Landscaping in Areas Prone to Standing Water

Do you live in an area with a high water table? Maybe you have a low-lying area that always floods after a rainstorm. In these instances, river rocks or decorative pebbles can be a lifesaver.

Mulching wet areas with pine bark nuggets or cypress mulch often leads to frequent clean-ups. Not only that, but you may also have to completely replace your mulch more often, driving up your gardening costs.

Using rock mulch is a great strategy for maintaining your water-prone landscape with less effort and long-term cost.

4. Bordering Established Trees and Shrubbery

Stone mulch naturally absorbs and holds heat from the sunlight, thereby warming the soil underneath. According the garden experts at Gardens Alive, this characteristic may help encourage plant growth in early spring, when the sun’s ray are starting to warm up but the ground is still chilly.

Not surprisingly, rock’s heat-retaining ability also occurs in summer. In this case, though, the heat may be too much for young plants or those with naturally shallow root systems.

But it won’t bother established trees and shrubs one bit. After a few years of growth, most healthy trees and shrubs have established a fairly extensive root system. Since they reach so deeply into the earth, older plants are unlikely to feel any ill effects from rock mulch.

So rock mulch can be a great way to liven up your established landscape features safely and for the long term.

5. Creating Drought-Resistant Plantings

Certain plants tolerate or even prefer warm, dry soil. These plants are often native to desert areas of the world or those that have dry, sandy soil (like the Mediterranean region).

A drought-resistant perennial in a rock mulch bed.

Here are just a few examples:

  • Lavender
  • Cacti
  • Trumpet Vines
  • Succulents
  • Artichoke
  • Marjoram
  • Rosemary
  • Sedum

Landscape rocks are ideal for recreating these plants’ native habitat, helping them thrive with less work on your part.

6. Bordering Your Hardscape

Hardscaping involves using non-living decorative elements in your outdoor space. These are a few popular hardscape features:

  • Decks
  • Fountains
  • Gazebos
  • Brick, concrete or stone patios
  • Retaining walls
  • Fencing

Sine these landscape elements are so striking on their own, a rock mulch border can be a fitting backdrop that complements the bold look. In this photo, you can see how the stone mulch creates a clean, finished look without competing with the intricate brickwork in the pathways:

A landscaping bed filled with shrubs and small perennials, with a rock mulch top layer.

Here’s another look at how stone mulch can complement hardscaping:

Rock mulch border for a flagstone path.

When To Use Wood Mulch

Landscape rocks have much to offer in terms of appearance and maintenance. However, they’re not appropriate for these three types of garden beds:

  • Vegetable Gardens
  • Fruit Orchards
  • Annual Flowerbeds

Wood mulch is your best bet in these instances, and here’s why:

  1. Wood is organic material that breaks down over time, enriching the underlying soil with essential nutrients, which rock mulch does not do. Fruits, vegetables and annuals need high amounts of nutrients to produce abundant crops and blooms.
  2. Vegetables and annual flowers tend to have shallow roots that are more vulnerable to burning and temperature fluctuations. While rock absorbs sunlight and holds heat, wood mulch deflects sunlight, keeping the soil at a more constant, cooler temperature.
  3. Wood mulch forms a dense, protective barrier that slows down evaporation from the soil. Meanwhile, moisture readily evaporates from the gaps between rocks, leaving your shallow-rooted plants thirsty.
  4. Wood chips or shreds are easier to move when you’re ready to plant new plants. Once you’ve placed rock mulch, it’s heavy to move, and planting veggies/annuals in rock-covered beds can be a big chore every spring.

In these situations, compost mulch, grass clippings, shredded leaves or hardwood mulch are far superior.

If you’d like to get some more stone and wood mulch landscaping inspiration, check out this video from Tatyana Holovina:

Frequently Asked Questions about Rock vs Mulch

If you’re looking for a more natural look, pea gravel and crushed gravel are two fantastic options. For creating a defined border for landscape beds or paths, river rocks work perfectly, and their larger size keeps them firmly in place. If it’s color you’re after, lava rocks, slate and chips are your best choices.

It depends on the type of plant. For established trees and shrubs, the root system is deep enough to withstand any extra heat that rocks absorb from the sun.

However, for younger or more delicate plants, stone mulch will likely warm the soil too much, lead to excessive moisture loss, weakened roots and ultimately, unhealthy plants.

Even though large rocks can make an attractive shelter for certain types of bugs, the smaller stones used for rock mulch typically don’t make a good home for insects.

In fact, organic mulches tend to attract far more bugs and small rodents than rocks. If you’re looking to deter pests around your home, rock mulch can be a big help.

Final Thoughts

Rock mulch is a great low-maintenance, high-durability material that will last for many seasons to come, looking great and saving you time and money over the long run.

Although there are places where standard mulch is a better fit than stones, many areas of your home landscape can benefit from an application of rock mulch. So don’t be afraid to think outside the usual mulch box and consider a layer of rocks.

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