Rock Mulch vs Organic Mulch — Which Is Best?

Last Updated on November 21, 2021 by Grow with Bovees

So you’ve finally got round to that landscaping project in your yard and now you have to decide whether to use something traditional like wood chippings or to go with the trendier new alternative of rocks instead of mulch.

So, organic mulch vs rock?

It can be tricky to decide which is the most cost-effective and better looking for your garden project.

Here at Bovees, we know these decisions can be hard so we’re going to look into the pros and cons of both and give you some tips on figuring out what would work best for you.

Let’s get mulching!

What is Mulch?

First of all, it may be a good idea to make sure we’re on the same page when we talk about ‘mulch’.

Basically, a layer of mulch can be any sort of covering that is spread or laid on top of the soil.

It’s used to suppress weeds, prevent frost damage, help retain moisture and just make the garden look more attractive than having just bare soil around your plants.

You can use many materials as mulch, both organic and inorganic.

Types of Organic Mulch

Organic coverings decompose and add nutrients back into the soil to help plants grow, which is great, but does mean it will have to be replaced every couple of years or so.

If the traditional mulch is really woody and dry, the slower it will decompose and the least amount of goodness it will release into the soil.

Organic materials include:

  • Wood Chippings
  • Pine Needles
  • Shredded or Chipped Bark
  • Newspaper
  • Shredded Leaves
  • Grass Clippings
  • Straw

Types of Inorganic Mulch

Inorganic materials have the advantage that they take years to decompose and so will not need replacing for a long time (if at all), so very low maintenance.

The downside is that they don’t benefit the soil at all apart from helping suppress weeds and retain moisture.

Inorganic materials that can be used include:

  • Stones and Gravel
  • Landscaping Fabric
  • Black Plastic Sheets

It’s worth noting that black plastic will decompose eventually and when it does, it can contaminate the soil. Also, landscape fabric will rot in a few years and as it does so, will allow weeds through.

For the purposes of this article and to try and keep it simple, from now on when we use the term ‘mulch’ on its own we are only talking about organic materials and not rocks or fabrics.

Landscaping with Rocks and Mulch

Now we have the definitions out of the way, time to move on to what type of mulch or rock to use in your garden beds.

Should you just use one or the other?

In many scenarios, we often recommend it’s possible to use both. Rocks and fresh mulch benefit and compliment each other and you can enjoy the properties of both whilst lowering the overall maintenance of your yard.

For instance, you could highlight some beds by using landscaping rock and building a retaining wall, while on others use just organic materials or use both together to create a contrast.

Where you have areas that you don’t regularly plant annuals every year, that would be a place to use just rocks or gravel as mulch to reduce maintenance and make that fall/spring cleanup a lot easier!

In other places where you want to enrich the soil whilst making it easy to add new plants for bedding etc., you could use bark or wood chips, for instance, which will also still help lessen weed growth as well.

Using Rocks for Your Landscaping Project

There are many different types of stone mulch you can use including river rock from river beds, crushed gravel, red lava rock, and many others. Usually, we refer to these coverings as decorative gravel or landscaping rock.

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Natural rock or gravel is the low maintenance option when it comes to comparing mulch vs rock, with the natural color giving a very nice, aesthetic appeal to the outdoor areas of your home, in the form of a rockery, for instance.

A big benefit is that you will not need to top up the gravel (or apply a ‘top dressing’ as it’s commonly known) every year. In fact, it will only be required every 5 years or so typically and even then you will only need to apply a thin layer of stone to bring it back to its former appearance.

Natural stone can age and become weathered which may be a good thing for some varieties of rock mulch if you like that look, but if you want to restore the color then a quick session with a power washer will be enough.

Be careful when cleaning smaller stones so that you don’t wash them away! Use a lower setting on your washer rather than full blast.

Clearing the leaves in the fall or doing some spring cleaning after a long winter is made a lot easier too as you can just use a powered leaf blower to blow out plant debris, leaves, grass cuttings etc. (again, beware with smaller sized gravel mulches though that you don’t dislodge them).

Of course, another feature, which is both a pro and a con depending on what you want, is that landscaping gravel will never deteriorate or break down after its initial installation.

Flower Beds With Rocks Instead of Mulch

As we mentioned above, we would not recommend you add rocks as a covering on your flower beds where you are often planting annuals and bedding plants as rocks can be difficult to dig out.

If you do want to use landscape rock beds in those areas, one idea is to use ornamental, decorative pots that fit with your yard theme to plant your annuals in. Small rocks or pebbles are also great for putting on top of your potted plants for an attractive look.

Where you just have perennial plants and shrubs, however, a rock vs mulch covering will work well as will not hurt your plants or restrict their growth in itself. Rock coverings do tend to retain the heat though and increase soil temperature.

This could dry out the roots of some plants or affect their leaves so be careful if you have delicate stock in regions that have hot summers.

Do Rock Beds Stop Weeds?

One of the main things you would use a soil covering for is to stop weed germination and stones or gravel is great for this, especially if laid on top of some landscape fabric as well. This really stops weed seed from getting in.

You will also find that using river rocks and other decorative stone helps control erosion of the soil and will increase drainage, so they are great to use in wetter areas or places subject to a lot of water damage due to heavy rain.

How Expensive is Rock Mulch Landscaping?

It’s true that decorative landscaping stone for river rock flower beds or putting rock around trees etc. will be more expensive to buy and put down in the first place, but we think that over the years, it will prove to actually save you money.

Stones will need far less maintenance and topping up over the years, so there are big savings in both time and money as opposed to using organic mulch.

Rocks, stones and gravel can be purchased in smaller bags for ease of transporting and using to top-dress from time to time, but you will make huge savings by buying a bulk bag which is usually sold by the ton.

You can also have it delivered very cost-effectively this way so it’s one option to definitely consider.

Gravel and river rock prices will vary by region so be sure to have a look around local stone merchants or landscape supplier to see what’s available locally before settling on a particular variety of rock mulch.

Let’s now round up the pros and cons of using rocks instead of mulch.

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Pros

  • Adds a definite creative appeal
  • Will probably be cheaper in the long run
  • Does not break down or decompose
  • Protects soil and plant roots from freezing and frost
  • Great soil erosion protection
  • Prevents weeds and weed germination
  • Great for areas prone to rain
  • Increases drainage in wet areas of your yard
  • Lower maintenance
  • Easy to clean up in fall and spring
  • Great for plants that like a little extra heat
  • Les likely to be dug up by animals and pets

Cons

  • Does not break down naturally and add nutrients to the soil
  • More expensive initial outlay
  • Not the best for areas where you are often planting new annuals
  • Can damage plants sensitive to increased soil temperature

Landscaping Projects Using Mulch

If you prefer the more earthy look of traditional mulch using organic material then using decorative landscaping mulch is something you will want to look into.

For longer-term mulching that you want to look good for a few years, we recommend only using shredded or chipped bark mulch, or hardwood chippings, and not things like shredded leaves or grass.

Although all mulch adds nutrients and gives back a lot to the garden, materials like bark and chipped wood are a lot more pleasing to look at.

Unlike rock mulch, organic materials are a very beneficial soil cover for your flower bed and around trees as they will rot down over just a couple of years or less, providing important nutrients for the soil and generally improving the condition of your flower beds.

Does Wood Mulch Provide Weed Control?

Mulching is a natural barrier to prevent weeds from germinating and suppressing their growth, whilst making it very easy to plant new annual plants, flowers, and bedding in your borders and flower bed whenever you want.

Like rocks, using a weed barrier fabric will really help with this.

Mulches with chipped bark, wood chips and the like are a great way to help the soil moisture retention and insulate it from frosts and freezing temperatures, but can lead to problems in areas where drainage is not good.

You also do not get the issues with heat build-up that you find with rocks, making organics much better for heat-sensitive plants.

How Much Does Mulch Cost?

When comparing the prices of organic wood mulch vs rocks, it will be lower to start with, but as you will need to top it up every year, then there is an ongoing cost.

At some point, which could be within 2 or 3 years you will need to dig some of it out and replace it completely.

Bear in mind as well that as you do your yearly cleanups in the yard to get rid of debris from leaves etc., you are bound to remove some as well so that will need to be replaced with fresh mulch.

You can find a large array of the different types available at many home and garden stores or other suppliers. so it’s very easy to get hold of at reasonable prices in easy to carry bags.

As with landscaping stones, if you can buy in larger quantities then it will be much cheaper. It’s usually sold by the yard or 1/2 yard and available for both delivery or pickup.

Is Mulching Worth the Effort?

Overall we think organic mulching is well worth the time and effort as it really benefits the soil and your plants, plus it can make your flower beds look great.

But as with rock mulches, there are several things to think about so let’s recap the pros and cons.

Pros

  • Adds a nice look to your yard for great curb appeal
  • Great for areas you want to plant regularly
  • Helps soil water retention
  • Protects soil and plants from the heat of the sun
  • Provides beneficial soil microbes as it breaks down
  • Provides soil with protection from frost and freezing temperatures
  • Natural weed control
  • Far less expensive initially

Cons

  • Requires yearly top ups
  • Not maintenance-free
  • Not as good at weed prevention than stone
  • Can be costly over the years
  • Needs replacing completely in just a few years
  • Not the best solution for wet areas
  • Can be dug up by pets and animals
  • Not so good at preventing soil erosion
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Summing Up — Rocks Vs Mulch — Which Is Better?

There are a few things to consider as the choice of mulch can add loads to your garden or flower bed after planting new trees, shrubs and flowers or starting a new landscaping project.

There’s no denying that some type of organic wood mulch variety, landscaping rock or gravel mulch really adds a lovely finishing touch and can make your yard look neat and tidy.

But of course, it matters what type you use and where you use it and as we mentioned earlier, there is a case for using both types on your flower beds and around your trees as together, they create a great effect.

Let’s quickly sum up the key differences.

Moisture Control: With organic wood mulch, it really does help to reduce water evaporation and so you may find you need to water less, saving you some time. Rocks or gravel do help a little in this regard, but definitely not as much.

Drainage: The other side to this is of course improving the drainage of your soil in wetter areas. Rocks or stones will definitely help here whereas organic materials are likely to make it worse.

Soil Conditioning: As we know, as organic mulches break down, they provide the soil with nutrients. Rock mulches on the other hand provide nothing and may even mess with the pH of the soil in some cases turning it more alkaline, so it’s worth noting which plants prefer acidic soil conditions in your garden.

Weed Prevention: Both types of mulches will slow down the growth of weed seeds and are an effective weed suppressant, particularly when paired with some weed barrier fabric. Even tougher weeds are stopped when using weed tarp.

Of course with organics, there is a fair amount of ongoing maintenance required to prevent the germination of weeds. Rocks will just need a quick blow-over with a leaf blower to make sure there is not a spot for weeds to grow.

Temperature Control: Rocks are not as good at regulating the temperature of the soil as organic materials, and may even cause problems here. Organic mulches are great at keeping the soil cool in the summer and warm in the winter.

Soil Erosion: Rocks are great at keeping the soil in place, even in heavy rain. Organic materials do help, but can be washed or blown away themselves so are not quite as good.

Maintenance: You will find you have a lot more maintenance to do on your wood or bark mulches than with a stone covering. So if time is a factor then that is definitely something to consider before you start your project.

Cost: Rocks, gravel and stones are going to be more expensive to install to start off with, but over several years, you will most likely find that they have cost you less than putting down organic materials which need constant topping up and replacing.

Wind Resistance: This may not be something you’ve thought of, but if you live in an area that gets a lot of storms and high winds, materials like hardwood chippings and bark are going to get blown away very easily. Rock mulches will stay in place in these conditions making them a more permanent solution.

Pets & Animals: Rock and stone mulches are far less likely to be dug up by passing animals or your own pets than organics. Less nasty surprises when you’re gardening!

Fire-Proof: Finally another consideration you may not have thought about, but especially important in some areas these days. Organic materials such as chipped bark mulch, wood finings, pine bark, pine needles etc. are flammable especially when very dry. If you live somewhere that is prone to fires, you may like to use more in the way of rocks and gravel instead.

Conclusion

And there you have it.

Our super guide to organic mulch vs rock mulch when working on your garden project.

Which one should you use? That really depends on you, your outdoor space, where you live and what you want to achieve, but hopefully we’ve given you enough information to make an informed decision on what is best for you.

Happy mulching!