Some people think that you can never mulch too much—a common myth: The deeper the mulch the harder it is for weeds to grow. WRONG!
Mulch is used to help insulate the roots when it’s cold, and to help keep moisture in when it is hot and dry.
Myth #2: The type of mulch doesn’t really matter.
We disagree. When you use natural, organic bark mulch that has compost mixed in, it will create a nutritional value to the plants over time. In contrast, dyed mulch that is created from old pallets, is dead material and has an artificial colorant added. While you may like the look of this product, it has no nutritional value for the plants and is slow to decompose. Using non-organic mulch year after year may enhance the appearance of the bed, but you will need to replace plants sooner, because they are actually dying a slow death or suffocating.
What about the depth of the mulch?
If you use more than 2 inches of mulch, plants actually begin to suffocate. Plants will produce more fibrous roots in surface areas where it is easier to grow, especially for those that tend to have shallower root systems—like evergreens (see photo A below), maples and birch trees. This will weaken the overall root system—and also harbors insects and moisture.
When mulch has built up over the years on the trunk it needs to be removed to prevent rot in the trunk and suffocation (see the photo B).
At M.J. Design, we use Kurtz Bros. Custom Hardwood mulch made from natural organic material that will decompose over the year—and we strive not to lay more than 2 inches of mulch coverage.