Disadvantages of Mulch
You’ll frequently hear how great mulch is for your garden with very little thought on the disadvantages. Mulch can actually have quite a few disadvantages that you may want to consider.
Does Mulch Attract Pests?
If we understand that mulch can provide a warm, dark, moist, woody environment with plenty of places to hide and a great supply of food, it’s not difficult to conclude that mulch creates the perfect environment for many pests.
This isn’t normally a problem unless you plan to mulch near your home, especially touching your home.
Types of Pests That Mulch Might Attract
You’ll find that several harmless pests will be attracted to mulch such as ants, beetles, snails, slugs, and earwigs.
These harmless pests might become a food source for spiders, wasps, and even garter snakes.
Some less desirable pests that might be attracted to your mulch are wood mites, roaches, and worst of all termites.
In the same way that a deep layer of mulch protects your plants, it does the same for termites.
If termites end up too close to your home, they might decide to feed on the wood inside.
Termites enter your home through cracks in your concrete, and by then building shelter tubes inside. Once they’re in they move onto the wood inside your home.
Is Dyed Mulch Harmful to My Garden?
Some of the most popular mulch will be dyed black, brown, or red. Typically the dye is actually harmless to your plants and soil. The problem is actually the material that’s being processed into mulch and then dyed.
Some of the most commonly sourced materials for this type of mulch are wooden pallets, leftover construction material, and material claimed from construction tear-downs.
This type of wood is typically treated to resist moisture, which will dry out the soil and that treatment process is often chemical.
These treatments have the opposite effect of what you’re looking for from mulch, which is water retention. This also slows the decomposition of the wood, which will often outlast the dye, leaving you with faded, questionably sourced wood that may compromise plant health.
The most harmful wood comes from sources with chemicals that are now banned but were commonly used several decades ago.
Have you ever wondered why dyed mulch is less expensive than other mulches, even though additional processing and materials (dye) are necessary to produce it?
Does Mulch Catch on Fire?
Aside from the obviously neglectful disposal of cigarettes, there exists a perfect set of environmental conditions that can cause the mulch to heat, smolder, and combust. The national weather service will often issue ” Red Flag Warnings” when these conditions are met. Some of these conditions include wind speed, relative humidity, atmospheric stability, dry frontal passages, lightning, and fuel (in this case mulch) dryness.
You can find out more about red flag warnings in this MDPI article. Fire | Free Full-Text | Verification of Red Flag Warnings across the Northwestern U.S. as Forecasts of Large Fire Occurrence (mdpi.com) This is another reason to keep mulch away from the side of your house.
I’ve seen this warning issued only once in my life, and it was issued the day after some fresh mulch at work had reached the smoldering phase, proving to me that these warnings are relevant.
How Expensive is Mulch?
Mulch can have a wide range of costs depending on the type that you buy, the amount that you buy, and if you choose to install it yourself.
The cheapest option that you will find is by the bag. Bagged mulch is typically sold in 2sq ft. bags. The least expensive that I’ve seen have been 3 bags for $10. This was for mass-produced, dyed mulch at a hardware store. If it’s not on sale, you can find bags that cost between $4 and $10.
The cost of mulch by the truckload delivered can range from $120-$450+ depending on the type you choose. The cost for installation can range between $20-$45 an hour, with some companies building the labor into the cost. This can almost double the cost of mulching.
Are There Plants That Are Harmed by Mulch?
Not every plant will do well being covered by mulch. In fact, if you layer your mulch too heavily, mulch can have a detrimental effect on any plant. There is a reason why mulch suppresses weed growth.
If you pile mulch too high around trees in particular, you run the risk of not allowing water to make it to the roots which is obviously detrimental to plants.
The effect is also compounded when the mulch heats up due to decomposition. This raises the soil temperature and can keep water that has been absorbed through the roots not to make it all the way up the trunk of the tree.
Plants and vegetables with woody stems can experience root rot if the mulch around them touches the stem especially if you use too much mulch.
Grass clippings, if used fresh can burn your plants as they start to decompose.
How Often Do I Need to Reapply Mulch?
Unless you’re using an inorganic mulch, such as pea gravel, you’ll need to replace your mulch. There are several factors that will determine how often you’ll need to do this.
Mulch can wash or blow away- If you use mulch that is too light (usually pine, or chunked mulch) there is a risk that it can wash away little by little, especially if you experience heavy rain or have applied your mulch on a slope (people often mulch a slope to avoid mowing the slope.)
Mulch can fade in color- Remember the dyed, treated mulch that I mentioned above.
The materials used in dyed mulch are made to last, rather than break down. It can often outlast the dye that is used to give it a more vibrant color, leaving you with faded mulch that you’ll either have to remove or mulch right on top of it. If you mulch on top, you run the risk of over-mulching.
Even hardwood mulch will break down over time, faster if it’s a finer mulch.
Typically you’ll need to reapply within 1-2 years. Some larger, hardwood mulch that is well protected can last a little longer, however, all organic mulch will need to be replaced eventually.
Risks of Mold and Fungus in Mulch: A Gardener’s Concern
While mulch undeniably enhances soil health and garden aesthetics, it’s not without its challenges, notably the risk of mold and fungus development.
These organisms flourish in the damp, warm environment mulch provides. While many types of mold and fungus play a benign, even beneficial role in the decomposition process, there are exceptions. Certain strains can harm plant health, spreading diseases that compromise your garden’s vitality.
Beyond the garden, some molds pose health risks to humans and pets, particularly for individuals with allergies or respiratory conditions.
Aesthetic appeal is another consideration; a lush garden bed can quickly lose its charm to unsightly fungal growth.
Additionally, specific fungi, like the artillery fungus, can project spores onto nearby surfaces, creating stubborn stains on house sidings, vehicles, and outdoor furniture. Addressing mold and fungus early and effectively is crucial to maintaining the balance between mulch’s benefits and its potential drawbacks.
Key Takeaways and Quick Tips
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- Mulch can attract termites, wood mites, roaches, spiders, and snakes
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- The wood used in some dyed mulches can be harmful to your garden
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- Mulch can increase your risk of fire
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- The cost of mulch can be pretty high
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- Most mulch must be reapplied yearly
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- Certain types of mulch may contain weed seeds
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- Use straw mulch rather than hay
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- Sawdust can take nitrogen from the soil
Interested in a “Mulch” with virtually no downsides? Straw is the perfect option, find out why here.
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