Skip to main content

HappySprout may earn a commission when you buy through links on our site.

Is non-wood mulch safe for your garden?

People use mulch for various reasons such as controlling the soil’s temperature, improving the look of gardens and lawns, and supplying nutrients to both the plants and the ground.

Wood chips and bark are most commonly used when it comes to the wide variety of mulches on the market. However, gardeners will find that many other types of non-wood mulch are equally good.

In this article, we’ll discuss other mulch types that aren’t wood, why non-wood mulch is safe for gardens and could be better, and which mulch might be best for your garden.

Non-wood mulches

Before we get into specifics, let’s go ahead and list out a number of non-wood mulches out there. This list isn’t exhaustive because mulch can be comprised of a great many different materials. However, some of the more common are:

  • Rock mulch
  • Inorganic black mulch
  • Rubber mulch
  • Pine needles
  • Hay/straw
  • Cardboard and newspapers
  • Grass clippings or leaves
  • Coconut coir
  • Glass
  • Seaweed
  • Shells
  • Silver plastic
  • Cocoa beans

The list could continue, but you get the idea. Below are more in-depth details on the top three non-wood mulches on this list.

black mulch and stones

Rock mulch

Pebbles, rocks, gravel, stones … they can all be used as an alternative mulch for weed suppression and to retain moisture. One of the great benefits of rock mulch for your garden is the fact that you’ll rarely need to replace it. Additionally, rock mulch tends to complement the style of modern architecture. Of more importance than aesthetics to the gardener is the fact that rocks can help retain heat. In turn, this may help extend the growing season of your plants.

Entirely safe for the garden, rock mulch does have a few disadvantages, such as the fact that it’s not biodegradable. Rocks don’t wear away easily, and they don’t put nutrients back into the soil as some other mulches do when they decompose.

Inorganic black mulch

While natural black mulch is essentially wood chips that have been dyed black, black inorganic mulch can consist of black rocks, black plastic, etc.

There are some significant drawbacks to black inorganic mulch, making it a less attractive choice for gardeners. While it can help to suppress weeds, if it’s made of plastic it can also kill beneficial organisms in the soil, increase the overall temperature of the garden during summer months, and you’ll have to install irrigation under it because it’s essentially waterproof.

On the plus side, inorganic black mulch can be beneficial in specific instances. For example, if you want to plant perennials or vegetables susceptible to the cold, black plastic mulch can increase the soil temperature and benefit these tender plants.

Not as damaging as black plastic, black rocks can also be considered a type of inorganic black mulch. If you decide to use them, you’ll need to make sure that you put them around plants that are already well-established. You won’t want your plants harmed due to temperature fluctuations.

With that said, some drawbacks for your garden include whether the rocks might crush your plant’s tender roots or compact the soil. Additionally, rocks can be cumbersome to maneuver if you’re working in a vegetable garden.

rubber tires recycled into mulch

Rubber mulch

Made up of rubber reclaimed from old, recycled tires, rubber mulch provides gardeners with some advantages not offered by wood mulches. For example, rubber mulch allows soil temperatures that can be higher and lower than wood mulches provide. This is because rubber mulch is an excellent insulator. Moreover, water is able to make its way around the individual rubber pieces that make up the mulch without being absorbed by the rubber at all. The rubber’s nonporous nature reduces unwanted plant growth, fungus, and acts as a barrier to weeds.

While this can be considered a better alternative mulch than inorganic black mulch, it still has some drawbacks. One of these is that like rock mulch, it doesn’t decompose and therefore doesn’t return any nutrients to your garden’s soil.

You’ll also want to give attention to the type of recycled rubber used. Some kinds may seep harmful chemicals and minerals into the ground that can hurt your plants. Usually, this isn’t a problem; but if large concentrations are leached out of the rubber, it’s a bad thing.

Why it all matters

When it comes to weed prevention, water retention, soil fertility, and temperature regulation, deciding which mulch to use is an important consideration. There are significant benefits to both traditional as well as non-wood mulches as well as certain drawbacks.

When looking at both traditional and non-wood mulches, you’ll want to think about such things as temperature regulation, whether you’ll need to add nutrients to your garden’s soil, overall cost, maintenance, contaminants, and mold.

Editors' Recommendations

Will Blesch
Former Digital Trends Contributor
Will Blesch is a copywriter, content writer, and someone passionate about anything that lets him discover more about this…
Gardening 101: Grow tropical plants in any climate year-round
Easy-to-care-for tropical houseplants
A potted pothos plant on a table

Succulents might get all the buzz for being low-maintenance plants, but don't count out tropical plants. Beloved for their lush leaves and beautiful variegation, tropical houseplants have a reputation for being finicky. While it's true that some require extra humidity and water, many are beginner friendly. Tropical plant care can actually be incredibly simple, especially if you start with one of these 6 tropical houseplants! No matter what experience level, personal taste, or budget, one of these tropical houseplants is sure to be a good fit for you.

Basics of tropical plant care
Many houseplants come from tropical regions all over the world. In nature, they usually grow beneath tree canopies in warm, humid environments. Because of how they naturally grow, these plants appreciate bright indirect light indoors or partial shade outside. Natural light will do, but grow lights can also supplement their needs. As long as the temperature is comfortable for you, it should be sufficient for a tropical plant. When it rains, snows, or gets too cold, bring your plants inside. When it's warm during the growing season, feed them a balanced fertilizer regularly and repot them with well-draining soil if necessary.

Read more
The 7 best types of Christmas trees to fill your home with holiday cheer
Everything you need to know about the most popular Christmas trees
Decorating a Christmas tree

Decorating your home for the holidays is so fun, and it's something the whole family can take part in. Choosing the Christmas tree is often an activity that families especially look forward to. And you can make a full day of it, bringing everyone out to pick the perfect tree.

This tradition is a great way to spend time together, and it ensures that everyone feels included in the festivities. But how do you know which tree is best for your situation? There are many types of Christmas trees to choose from, so it can be hard to understand how to narrow them down.

Read more
Which plants absorb the most carbon dioxide? Here are 5 air-cleaning plants to add to your home
Easy-care houseplants that will cleanse the air in your home
Areca palm

It doesn't matter if you live in the city or out on a homestead; clean air in our homes is something we all want. While using air filters and opening up windows are great ways to keep your air fresh and clean, sometimes they just aren't options. To get you started on cleaning up the air in your home, we'll be talking about the plants you can use to improve the quality of your air and the aesthetics of your space. Keep reading to learn which plants absorb the most carbon dioxide.

Why find carbon dioxide-absorbing plants?
There isn't anything you have to do to encourage a plant to absorb carbon dioxide and expel oxygen. It's what it does naturally! That goes for all plants, from a giant ficus rubber tree to a modest cactus. Any plant that uses photosynthesis to create its energy will improve your air quality. You can also find plants that absorb other toxic things from the air. For example, a bamboo palm will reduce levels of formaldehyde in the air as well. So if you're looking for a forest of air-cleaning plants, you're sure to find it.

Read more