Gardening Magazine

Bad Mulch?

By Thecitrusguy @SCCitrusguy
Mulch is one of those topics that everybody thinks it is a great thing. To a large extent that is true, however, there are bad things that can come from using Mulch that one should know about.
Let me start with the advantages of mulching your yard and plants.
Mulch conserves moisture and suppresses weeds. These two things alone one would consider a major bonus. With much of the country in a severe drought situation, conserving moisture would and should be the number one priority.
As for the suppression of weeds? I do actually know of a few people that enjoy pulling weeds. They tell me it is therapeutic. I sure do have a lot of therapy in my yard, but that is another story.
Soil temperature modification. It will keep your soil in a smaller range of temperatures without as many wild fluctuations.
Mulching can make a blah yard look a little more decorative and protect your plants from those evil lawnmowers and weedwhackers.
Bad Mulch?
So you love the idea of the good things Mulch can do?
There are about as many different kinds of Mulch as there are personalities.
Let's touch on a few of the more common ones.
Pine Straw: Here in the Southeast and probably elsewhere, this is a biggie on the hit parade.
Bad Mulch?
Some advantages to using Pine Straw are:
It doesn't float and wash away
Breaks down more slowly
It breathes better, doesn't compact as much as some, and allows for better water infiltration
It will also help your bird friends, because it is used frequently for bird nests and bird houses
I personally don't like it because it looks dull and faded very quickly. I also think it just looks messy, but that truly is just my opinion. I already know I will get letters saying things like, "you just need to see it applied correctly". I have, I still don't like it.
Tree Leaves: Tree leaves are Mother Nature's preferred mulch.
Bad Mulch?
Leaves from trees such as Oak which have a thicker texture make a better mulch than the leaves of trees such as Maples which are thinner. The thin leaves can compact down together to form an impermeable layer. They will eventually break down, just as in the forest, but your plants may suffer. Again, not one I like, it looks as if you need to rake and the first good wind storm that comes through, your neighbors will just LOVE you.
Cedar Mulch: Cedar mulch is ground material derived from the wood and foliage of Cedar trees.
Bad Mulch?
I actually like Cedar Mulch, it has two major advantages over other mulches. The oil in Cedar wood acts as a natural pest repellent, which, of course, also gives it that nice, evergreen smell that I adore. Of course, there are disadvantages. Being a hard wood mulch, cedar mulch, as well as the other hard woods, do break down over a long period of time. This decomposition can leach nitrogen from the soil and damage nitrogen-loving plants, which of course are pretty much ALL plants!
One other thing to consider about Cedar Mulch is, Cedar's positive qualities only remain active for as long as the mulch is relatively fresh. As the Cedar ages, the oil wears out, along with the scent and the pest-repelling quality.
There are, as I mentioned earlier, all kinds of mulches out there. Straw, Sawdust and Wood Shavings, Lava Rocks, Pebbles, Grass Clippings, the list seems almost endless. Each and every one of them has a list of Pro's and Con's, I just don't have the time or space to get into them all here.
There are two more mulches that I want to discuss however. They both are rather similar in appearance. They are made of two completely different materials, but I STRONGLY do not recommend using these when people ask.
They are Black Mulch and Rubber Mulch.
Bad Mulch?
I will admit, the black looks really cool and it tends to set the color of the plants off, but there are many problems associated with them.
First off, I hear the recycling people now, "but Rubber Mulch is made from used tires, do you want them filling our landfills?"
There are other uses for them that will not effect my plants health and wallet.
Rubber mulches tend to be more expensive that traditional wood mulches; some cost even twice as much.
Rubber mulches have a very distinct odor that isn't pleasing to a lot of people. To be fair, it does disappear over time, how long depends on weather conditions.
Sometimes the steel wires are still contained inside the pieces. You need to wear heavy duty gloves to avoid being cut or stuck with possible protruding wires. I won't even get into the area of always needing to wear shoes around this stuff.
One other possible problem is, the chemicals that can leach from tires into your soil.
Rubber Mulch provide no nutrients to your soil, however, they also do not rob any either.
As for the dyed Black Mulch. The wood pieces are dyed using iron oxide or vegetable dyes. Just to be on the safe side, check the labels to see what they have been dyed with to make sure that it is safe for the type of plants you are using it around.
Another problem with Black Mulch is the issue of staining. Some dyes will come off during rain or snow, which will cause the dye to move from the mulch and into the ground. The mulch will appear ugly and dried out. During constant sun exposure, the black mulch will gradually fade to an unsightly gray.
One of the major things I point out to people when I am asked about Rubber or Black mulch is temperature. I stated earlier that mulches are used to moderate temperatures. If you use a black colored mulch, it absorbs sunlight and gets very hot. Think about walking outside onto a concrete path in the middle of the day barefoot. Hot, right? Now go walk out onto the asphalt street. Get my point?
The black colored mulch will have the same effect on the plants roots. It will become very hot underneath. This will cause the mulch to decay faster, the roots will actually use more water and the plant will generally not be happy. Let's say you use it up North. The middle of Winter, a nice sunny day, the ground would normally be frozen, but you have Black Mulch down. The soil is warming up, the plant thinks it's Spring and starts to grow. Then a blizzard hits and the plant gets killed because it broke dormancy due to the warm soil.
There are people that swear by this stuff, I say more power to them. This is just my two cents worth.
There are a few basics to keep in mind. Mulch should be 2 to 4 inches deep. Too deep and it will suffocate the roots. I know the "Fresh Look" is what people like, so they add layer on top of layer every year. If this is you, remember to remove the old mulch first.
Many mulches will float away in a heavy rainstorm, use some kind of edging if this is a problem.
Anyway, this article is not to persuade you not to use Mulch, it is a good thing to do. I just want you to think about your situation and use the correct material.
I will leave you with one last parting shot.
Beware of Volcanoes! In recent years, people have begun mounding mulch around the base of trees creating the 'Mulch Volcano'. Tree bark is meant to protect the trunk. It works best in the air and light. If you pile mulch onto the bark, it is now exposed to dark and moisture. Bark will begin to rot, and rotted bark cannot protect the tree from insects and diseases. In fact, diseases grow better in this type of environment. Keep the mulch at least a few inches away from the bottom of the tree.
Hopefully none of YOUR trees have this look about them:
Bad Mulch?
Happy Growing!

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