Is Mulch Helping or Hurting Your Garden?

Like a woman’s make-up, mulch can instantly brighten up even the most drab planting bed, if applied properly.  The best part is, not only does it look great, mulch is great for minimizing weeds and keeping your plants healthy.  A layer of 2-3 inches of mulch will hold moisture longer than the soil itself after rain or watering, but mulch is often misapplied.                                                                                                                                                                          Mulch Mistakes  

"mulch volcano"

The most common mistake landscapers and homeowners make with mulch is creating a “mulch volcano.” It may seem best to pile mulch up around the tree to hold water and “insulate” the tree, but building a mulch volcano can actually choke the tree, so to speak.

When mulch is stacked high around the trunk of the tree, the tree will grow as if the mulch level is ground level. Its roots will spread from the base of the tree and then come to the surface and protrude up out of the ground as the mulch slopes back down.

If you’re wanting to apply a fresh coat of mulch to a bed that is already piled high, simply break up and rake away some of the existing mulch and then apply the new mulch. Oregon Tree Care has created a simple illustration to help. The same principle applies to shrubs and flowers. Never pile mulch higher than the original root ball or soil level you purchased the plant in.

Some of the most spectacular mulch beds can be found at Augusta National Golf Club, home of The Masters. I’m just a casual golf fan, but I watch The Masters each spring just to see the course itself, each hole beautifully adorned with Georgia pines, dogwoods, and azaleas.

The pine straw covered planting beds hardly rise at all from edge of the fairways, giving the impression of a pond reaching its grassy banks.

(photo courtesy of

Choosing the right mulch

Go to a big box store garden center and you’ll find a plethora of mulch options.  Which mulch is the right mulch for your planting beds?

  • Never use colored mulch.  Black mulch, red mulch, brown mulch, if it has been colored, don’t buy it.  You will never find a gardener worth his or his salt with black mulch in their beds.  Its full of dyes and chemicals that are bad for your plants and the environment.  It creates heat.  It fades into an ugly grey color.
  • Never use colored mulch.  Sorry, I get carried away.
  • Soil conditioner will hold moisture longer than any other mulch.  We covered most of the beds at Cheekwood Botanical Gardens with soil conditioner when I worked there and I use it at my house.  If you look inside the containers of the plants at the store you’ll see a high percentage of soil conditioner.  It costs a bit more, but it performs better, it gives a smooth carpet-like look to your beds, and its easy to spread.
  • If you don’t go with soil conditioner, shredded pine mulch and hardwood mulch are the only other two worthy options.  They are very similar in price and functionality, the only difference being that pine is a lighter wood color than hardwood.  I’ve never been a fan of the pine bark nuggets.  They look nice, but they are more expensive and don’t hold water as well as other options.
  • Pine straw can be functional, especially on a hillside, but I don’t recommend it for two reasons: 1)pine trees and thus, pine straw, are not native to Middle Tennessee, and 2)pine straw is just not as aesthetically pleasing in planting beds around the house.  If you happen to have pine trees, a big piece of property, or a high percentage of acid-loving plants, pine straw may be a good option.



2 thoughts on “Is Mulch Helping or Hurting Your Garden?

  1. Hi Matt- I am requesting permission to reuse your mulch illustration and photos for a publication I am making about proper landscape methods. If you agree, may I know how you want the credit to read. Thanks- Carol

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