10 Pros And Cons Of Black Mulch (Explained)

Grey much or dirt


When trying to maintain landscaping and keep weeds at bay, there are many mulch options to consider.

Organic mulches include mulches made from tree bark, pine straw, wood chips, and nuggets, while inorganic mulches include rock, crusher dust, rubber, and plastic.

Black mulch can be made from either organic or inorganic material.

Organic black mulch usually consists of wood chips or tree bark that has been dyed black using a water-soluble dye or stain.

Like with all mulches, black mulch has several good and bad qualities to consider before purchasing.


Pros Of Black Mulch


1. Makes A Decorative Statement

Front loader filling pickup and trailer with black mulch


Choosing any colored mulch adds another level of exterior aesthetic to your yard.

Black mulch makes a bold statement and can look great in contrast to the surrounding greenery.

It can make shrubs, trees, flowers, and any other plant in your yard pop.

It also gives the yard or landscape a natural, yet curated feel, adding curb appeal.

Because organic black mulch is dyed, the color stays vibrant longer than non-dyed mulches.

This keeps your yard looking clean and appealing for months, and maybe years, at a time.

Non-dyed mulches tend to break down faster and might need to be reapplied more often.

Also, by preventing weeds from sprouting and by killing existing weeds, black mulch helps keep your yard looking good longer and lessens the amount of manual labor it takes to maintain.

In short, you’ll end up weeding a whole lot less!

Black rubber mulch, often used in playgrounds and parks, adds beauty to those public spaces and makes them more welcoming to visitors.

The look of black mulch adds a level of care and attention to areas sometimes left unmaintained and overgrown.


2. Contains The Same Environmental Benefits As Nondyed Mulch

Gardener spills mulch under bush


As with any mulch, black mulch helps preserve the yard or landscape and adds essential minerals and nutrients back into the soil as it slowly decomposes.

Mulch, in general, also protects soil from erosion, helps regulate soil temperatures, and protects against soil-borne diseases.

In addition, mulch also helps soil maintain moisture, prevents weeds, and repels insects.

Dyed mulch, in particular, has been shown to repel insects, like roaches, termites, and crickets, that do not prefer the added dye.

Maintaining moisture is a huge pro in using black mulch.

Mulch lessens the amount of water evaporation keeping moisture trapped in the soil.

This keeps plants happier and healthier, especially during those long, dry summer months in some areas.

The black coloring also acts as an extra layer of insulation during cooler months, trapping sunlight and helping keep the soil warm.

By keeping a more regulated soil temperature, plants are less likely to experience temperature shock.

Because weeds consume the much-valued nutrients that other plants need to grow, preventing weeds is a huge benefit of using black mulch.

A thick layer of mulch suppresses new weeds from sprouting and can also kill old weeds upon application, by blocking the sunlight from reaching them.

Besides the application benefits of mulch, dyed mulches, in general, are usually made from recycled wood products, eliminating unneeded waste in the environment.

According to the University of Massachusetts Amherst Center for Agriculture, Food, and the Environment, “Besides the benefits of recycling waste wood materials, the reason why these wood materials are used for colored mulches is that they are very dry and readily absorb or adsorb coloring agents.”

Because this recycled wood would have most likely ended up in landfills, repurposing it is an ideal situation.


3. Can Be Just As Safe As Nondyed Mulches

Mulching garden beds with pine bark pieces


Since the dye itself usually comes from a natural source, most color mulches are harmless.

Black mulch is typically dyed with carbon or iron oxide-based dyes, making it safe to use in the garden or for landscaping projects.

In this case, the most important thing to look for is the wood source.

First, make sure the wood is sourced from a reputable and safe place.

Look for the MSC (Mulch and Soil Council) Certification Logo.

This states that the mulched wood did not come from CCA (chromated copper arsenate) treated lumber.

The MSC Certification Logo can be found on many retail mulch products at home and garden stores and ensures that those dangerous chemicals won’t leak into the soil and that the mulch is safe to handle.

In addition to chemical testing for CAA-treated wood contaminants, the MSC makes sure mulches have passed rigorous tests ensuring the mulch conforms to proper labeling requirements, passes laboratory testing, and passes random audit testing in retail markets.

To keep you and the environment safe, it’s best to only purchase black mulch with the MSC seal of approval.

The MSC also posts a list of certified mulches on their website making it easy and convenient to shop for the safest option.


4. Black Rock And Rubber Mulches Are Long Lasting

Senior woman mulching a flowerbed


Black rock mulch is completely natural, which makes it an appealing option to those that are especially environmentally conscious, and it won’t break down.

Black rock mulch is made from black lava rock that is crushed up into small pieces.

Because the lava rock is already naturally dyed black, there’s no need to add dye to the material.

Black rock mulch is extra appealing because the natural color won’t fade in sunlight, unlike some of the organic mulches that are machine dyed.

Unlike some other wood mulches that tend to float and drift away during heavy rains, black rock mulch stays in place.

Black lava rock is also lightweight, allows drainage, retains heat and moisture, and prevents soil erosion.

Also, lava rock is arid, allowing for better airflow and circulation.

Black rubber mulch is often made from recycled tires which are then ground up into one inch in diameter or smaller pieces.

This helps utilize old and used tires once again, instead of them uselessly laying as waste.

Repurposing old inorganic materials always helps the environment by giving new life to something that cannot naturally break down.

Black rubber mulch is often used in playgrounds or under outdoor gyms because of its inherent cushioning.

Its soft absorption helps prevent falls and injuries.

Like black rock mulch, black rubber mulch stays in place much better than wood mulches.

Because both of these mulches don’t break down, they need little attention or maintenance once applied.

This makes them ideal for public spaces or where a lot of foot traffic occurs.

Black rubber and rock mulches can also be more cost-efficient, as they don’t need to be reapplied nearly as often as black wood mulches.


5. Can Help Farmers Grow Better Produce

Green fresh cucumbers growing in the garden.


Black mulch also acts as an added barrier between plants and the ground, which can prevent plant rot.

Viny plants, such as squashes, melons, and cucumbers, that can grow along the ground often begin prematurely rotting from ground contact.

However, the added lift that mulch provides helps separate the vegetables or fruit from direct ground contact, allowing them to ripen properly.

Most people don’t think of plastic sheeting as mulch, but it’s a popular choice for commercial farmers.

Many farmers use black plastic sheeting to keep the soil warm and the moisture levels high.

Black plastic sheeting absorbs sunlight, holding in heat and helping young seedlings to germinate.

As with other types of black mulch, sheeting also holds moisture into the soil, preventing large amounts of evaporation.

The sheeting also acts as a thin barrier between the fragile plants and the ground.

Not only does the barrier act as protection from the direct negative effects of ground contact on plants, but it also prevents weeds from sprouting up.

This ensures that the plants themselves are getting all of the nutrients possible out of the soil without having to share the supply with pesky weeds.

Black plastic sheeting is an especially popular choice for strawberry farmers.


Cons Of Black Mulch


1. Can Contain Harmful Chemicals Or Be Made From Harmful Material

Mulch Dumping cart


As mentioned, not all black mulch is made from organic materials like tree bark and wood chips.

Some black mulch is from synthetic materials, like rubber and plastic.

Though much of these synthetic materials are recycled, the effect of using synthetic materials in a natural environment is questionable.

Needless to say, inorganic black mulch does not contain any nutrients for your plants or soil.

In addition to being highly flammable, black rubber mulch can contain toxic contaminants that are harmful to people, pets, and the environment.

Though most black rubber mulch is advertised as non-toxic and safe to use in gardens, gardeners and farmers typically prefer organic options.

Black plastic mulch consists of high- or low-density polyethylene plastic sheeting or woven polypropylene.

Some home gardeners use the plastic sheeting method to warm the soil a few weeks before planting begins and then remove it to prevent any possible negative effects.

Though plastic sheeting has not been proven to harm the environment, it’s inorganic, nonetheless.

In addition to being possibly made from inorganic material, some dyed mulches use pressure-treated wood as their main source.

This can be extremely dangerous to you and the environment, as some treated wood contains CCA.

Using this type of wood can introduce arsenic into your soil, which is harmful.

It can even be harmful to handle such wood.

If the mulch you are using is in question and you’re still determined to use it, it’s best to wear gloves when applying and spreading.

Iron oxide or carbon-based dyes have not been shown to be toxic to the environment, but they do often still leak elements back into the soil.

As the iron oxide oxidizes, iron seeps into the soil.

Also when mulching companies dye newer woods, they don’t absorb the dyes very well.

These dyes can easily come off on contact, making it important to use only dyed older woods and to wait for the wood to dry before use.

Though the dyeing process is usually safe, some cheaper and lower-quality black mulches are dyed with toxic chemicals.

Again, it’s best to do a little research before buying.


2. More Expensive

Mulching the garden takes time and effort


Black mulch typically runs higher than natural, undyed mulches.

According to Homeguide, black mulch runs at an average of $3 – $6 per bag, or about $40 to $60 per yard.

This is in comparison to an average of $0.89 per cubic foot, $1.78 per bag, or $24 per cubic yard for natural wood chips.

Of course, the cost of natural mulch can range in price drastically depending on what type of wood it’s made from.

For instance, pine bark is extremely affordable in comparison to cedar wood or cypress wood, which can cost an exorbitant amount of money.

Black rubber mulches run about $4.81 per cubic foot or $129.80 per cubic yard.

Though rubber mulches don’t have to be replaced as often, it’s still a large upfront cost.

Black plastic sheeting mulch runs at an average of $20 for a 4 x 100-foot sheet, while black lava rock costs an average of $80 to $240 per ton or $50 to $180 per cubic yard.

Buying in bulk is almost always cheaper than buying mulch by the bag.

Other costs to keep in mind however are delivery fees and installation costs (if needed).


3. Black Rubber Mulch Can Contain Hazards

Mulch and Manure


Because black rubber mulch is often made from recycled tires, there’s always a chance it can contain small bits of steel belt.

Though most modern rubber mulching goes through a magnetized process that pulls out any dangerous pieces, there’s still a chance of finding them.

This is especially true in some cheaper commercial rubber mulch products or if the source of the black rubber mulch is unknown.

Even though black rubber mulch is mostly advertised as non-toxic, there’s also always a chance of it containing unwanted chemicals and heavy metals.

These metals can leech into the ground, harming plants or leaking into nearby waterways.

Toxins that have been known to exist in black rubber mulch include zinc, arsenic, cadmium, and lead.


4. Can Cause Plant Problems

Withered flowers (Marigolds)


Adding black mulch to your garden can cause unwanted fluctuations in soil acid levels.

If black mulch is not used in a partially rotted state, it can pull much-needed nitrogen from the soil.

This unbalances soil acidity, which can damage plants or crops.

It can however be offset by adding nitrogen-rich fertilizer to your garden and by researching where your black mulch has come from.

Knowing its source can help determine what supplements are needed or not needed to keep your plants healthy.

In addition to changing the acidity levels in the soil, using black mulch in hotter climates can burn your plants.

Because black mulch absorbs a significant amount of heat from the sun, it also heats the soil below to higher than normal temperatures.

This heat insulation effect can be detrimental in warm climates.

By trapping the heat, the soil temperatures rise and can damage young or vulnerable plants.

If using black mulch in a warmer climate, it’s recommended to only lay it down in shaded areas.


5. Decomposes Slower

Mulching around the trunk of a tree


Because of the added dye, black wooden mulch decomposes slower.

This may sound great for some gardeners, but the truth is, the longer mulch takes to break down, the more toxins it starts to gather.

Those toxins can be harmful to plants and the soil.

Natural mulches are made to break down, releasing nutrients and organic material back into the soil.

Because black mulch breaks down slowly, it can disrupt the soil’s delicate ecosystem.

The breakdown process is so important because it keeps the soil moisture at a proper level, and without the added nutrients, the soil can turn into unusable dusty dirt.

This can, in turn, make for poor gardening and inhibit plant growth.

Wood requires nitrogen to break down, so it can disrupt the natural nitrogen levels when wood takes longer than normal to break down.

Because of black mulch’s nitrogen consumption during its slow decomposing process, maintaining the proper nitrogen levels in the garden or landscape is more time-consuming, requires more maintenance, and takes some research.



There are clear pros and cons to using black mulch.

With many types of black mulch to consider, it’s best to focus on your specific garden or landscaping goals and weigh the benefits with the negative effects.

For instance, if you care more about the overall look of your yard, black mulch is a great option.

Using black mulch is also a good choice if you don’t plan on reapplying your mulch often, as it lasts much longer than natural mulch.

If you decide to go with black mulch, decide what type of black mulch you want by factoring in the pros and cons of that particular mulch.

You might not want an expensive black rubber mulch in your organic garden.

However, if you’re looking to safely pad your child’s backyard playground, this is a viable option.

If you’re a serious gardener or farmer, black plastic sheeting mulch is a great way to protect your plants as they start to grow, locking in air and moisture.

You’ll surely produce a better crop and harvest.

If you don’t mind putting a little extra work into maintaining proper soil acidity levels, black wood mulch is also a good choice for home gardeners.

As with most things pertaining to your home and the environment, it’s important to weigh the pros and cons and determine what works best for your specific needs.

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