Bark Mulch Vs. Rock Mulch: What Type of Mulch Should I Use?

Filed under Misc by Lauren Cook on .

    Trying to decide what type of mulch to use in your landscape?  With all the information available on the internet these days, it can be difficult to decipher what type of mulch is best for you.  I've tried to lay it all out for you here so you can make the best decision for you.  If there is anything I've missed, please let me know and I will try to address it!

Most of the best landscape contractors in southern Illinois prefer using hardwood bark mulch for shrub,  perennial and annual plantings. The plants choose bark everytime!

Bark Mulch:  
                         The most commonly used type of bark mulch in Southern Illinois is made from shredding the bark of hardwood trees, mainly oak and hickory.  It is a dark brown color, but  can be dyed red or black.  Bark mulch is also available in pine and cedar.  Bark mulch is usually finely-shredded and has an earthy odor to it, especially when it is first spread.

Cost Installed:  $0.70 - $0.80 per square foot






  Easiest and cheapest to install


  Adds organic matter to your soil as it decomposes


  Retains moisture in soil, so you water less frequently


  Dark, brown color contrasts well with plants and lawn


  No need for weed barrier or edging material


  Soft and easy to walk on



  Must replace every 1-2 years

  Attracts insects

  Color fades in areas exposed to direct sunlight

  Can wash away in areas that flood or beneath downspouts


Rock Mulch:
             Rock Mulch is any type of decorative gravel used as groundcover.  Gravel pieces can range in sizes from pea-size to fist-size and come in a variety of colors.  Rock mulch is usually mined from the bottom of river beds.  The price per ton can vary greatly depending on where the rock was sourced from and it's proximity to where you purchase the stone.

Cost Installed: $1.50 - $3.00 per square foot (Includes weed barrier)



  Does not need to be replaced every 1-2 years.

  Available in a huge variety of colors, shapes and sizes

  Will probably cost less than mulch in the long run, since it will only need to be installed once.

  Larger sized (1.5-3”)rock mulch makes it easy to blow leaves and plant debris out of your beds.

  Rock mulch containing very angular pieces work well on slopes.



  Must keep gravel areas clean of any leaf or plant debris, otherwise weeds will begin to grow in between weed barrier and gravel

  Gravel can be expensive and difficult to install (Rock is heavy!)

  You must install weed barrier underneath all gravel, as well as an edging material to keep gravel out of your lawn.

  Some areas of rock mulch might get a little thin after a few years and will benefit from topdressing the gravel.

  Quarries can run out of gravel.  The colors, sizes or prices of rock mulch can change over time and make it difficult to match if you add more gravel to your landscape at a later date.

  Difficult to add or replace plants once gravel and weed barrier is installed.

  Rock mulch can get very warm on hot, sunny days.  You must make sure to choose plants appropriately.



Now, some of your most common mulch questions, finally answered:

Does Bark Mulch Attract Termites?

            Any kind of organic matter that you put near your home is going to attract insects.  Whether it be groundcover, shrubbery or lawn.  If you are using bark mulch near your home, the termites will NOT be attracted to the the mulch as food.  Termites do not eat the bark, but they do eat wood and wood chips.  That being said, termites might be attracted to living below your mulch because mulch tends to retain moisture in the soil and insects are attracted to moisture.  To reduce your risk of termite damage, I recommend the following:

-        When installing bark mulch, leave 2-3” between the top layer of mulch and the bottom of the siding on your home.

-        Never use fresh wood chips as mulch around your home!  By using wood chips as mulch, you may be introducing new insects and diseases to your landscape. Wood chips also take available nitrogen from the soil to facilitate decomposition and leave less for the plants!

-        Make sure you have proper drainage around the foundation of your home.  If you notice wet areas, you may want to look into re-grading certain areas around your home and/or repairing or adding gutters to your home.

-        Hire an exterminator to treat your home regularly. 

Can Bark Mulch Start on Fire?

            Bark mulch will NOT spontaneously combust into flames.  However, a lit cigarette tossed into a bed of bark mulch on a hot, summer day in the middle of a drought has been known to ignite a small flame or at least smolder a bit.  When choosing what type of mulch you will use, remember to take into account the location or setting.  Commercial properties with high amounts of public traffic might be better off using rock mulch in order to prevent this liability or at least providing a receptacle for cigarette butts.

Which Mulch is Best for the Plants?

            Bark mulch is better for plants because as it decomposes it will add organic matter to your soil, improving the health of the soil.  It also retains moisture in the soil, so you have to water less frequently.  Bark mulch will allow perennials to spread.  Rock mulch will not.

How do I Know How Much Mulch I Will Need?

            Bark: Figure out the area of the space you are mulching and divide by 100.  This will give you the number of cubic yards you will need to spread it 2-3” thick.   One cubic yard is about enough to fill up the bed of a ½ ton pick-up truck.

            Rock:  Figure out the area of the space you are mulching.  For larger sized gravel (1.5-3”), divide this number by 80 to get the number of tons you will need.  For medium sized gravel (.75-1.5”) divide this number by 100 to get the number of tons you will need.  For small, pea-sized gravel (.25-.75”)divide this number by 120 to get the number of tons you will need.  These numbers will give you the amount you need to spread the gravel 1.5-2” thick.

What Other Materials Can be Used as Mulch?

Pine Nugget Mulch

Rubber Mulch (Note: Rubber leachates may contain minerals and/or compounds that can become toxic to plants at high concentrations)

Pine Straw


Grass clippings

Mushroom Compost


Nut Shells

Wood Chips (Note:  Do not use fresh wood chips on plants!  The process of the chips decomposing could steal nitrogen from plants, resulting in stunted and/or yellowing growth on your plants.  Fresh wood chips can be used to mulch garden paths.)


Greenridge Landscaping - southern Illininois Landscape Designers