Is Rubber Mulch Good? The Ultimate Guide to Choosing Safe Mulch

 Rubber mulch—made from recycled tires—is often promoted as a long-lasting, low-maintenance alternative to traditional organic mulch. But is rubber mulch good for your garden, especially in Denver’s climate?

As Denver landscaping professionals, we’ve seen many homeowners drawn to rubber mulch for its durability and minimal upkeep. However, the question “Is rubber mulch safe?” for plants, soil, pets, and the environment deserves a deeper look before you invest.

This guide covers:

• What rubber mulch is and how it’s made

• The pros and cons of rubber mulch

• Whether rubber mulch is harmful to soil, plants, and pets

• Best uses for rubber mulch in Denver

• When it’s a smart choice—and when it’s not

Whether you’re considering rubber mulch for your yard, this guide will help you make the best decision for your landscape and the environment.

What Is Rubber Mulch?

Rubber mulch is created by shredding recycled tires into small chips or nuggets. These pieces are processed to remove metal components, cleaned, and often dyed in colors like brown, black, or red to resemble wood mulch.

The manufacturing process includes:

• Collecting used tires

• Shredding them into uniform pieces

• Removing steel using magnets

• Cleaning to eliminate contaminants

• Coloring with synthetic dyes

This process diverts millions of tires from landfills, which manufacturers highlight as an environmental benefit—but the full impact is more complex.

Benefits of Rubber Mulch

Rubber mulch does offer real advantages, especially for specific landscaping applications.

1. Long-lasting and low maintenance

• Doesn’t decompose

• Lasts 8–10 years or longer

• Resists Denver’s freeze–thaw cycles

• Requires little to no annual refreshing

2. Excellent water drainage

• Water passes through easily

• No pooling around plant bases

• Reduces standing water and mosquito activity

3. Strong weed suppression

• Blocks sunlight from reaching weed seeds

• Creates a dense, long-lasting barrier

• Nearly eliminates weeding when combined with landscape fabric

4. Fire resistance

• More resistant to ignition than dry wood mulch

• Safer for Colorado’s dry summers

• Still melts and emits toxic smoke under direct flame

5. Pest resistance

• Doesn’t attract termites, ants, or rodents

• Useful around tree bases and problem areas

6. Made from recycled materials

• Reuses millions of scrap tires

• Reduces demand for new materials

Drawbacks of Rubber Mulch

For living garden areas, rubber mulch comes with significant disadvantages.

1. Chemical leaching

Rubber mulch can release small amounts of:

• Zinc

• Heavy metals

• Polycyclic aromatic hydrocarbons (PAHs)

High zinc levels are toxic to many plants and soil organisms. Colorado’s dry climate slows leaching, but it also slows natural detoxification—meaning contamination can accumulate over time.

2. No soil improvement

Rubber mulch:

• Adds no nutrients

• Doesn’t support soil microbes

• Can repel water when compacted

• May reduce mycorrhizal activity

Over time, soil fertility declines, affecting long-term plant health.

3. Heat retention

Rubber mulch absorbs significant heat:

• Raises soil temperature

• Stresses shallow-rooted plants

• Increases watering needs

This is especially problematic in Denver’s intense summer sun.

4. Odor and VOC emissions

New rubber mulch can release:

• Strong tire odors

• VOCs like benzene and toluene

Smell and emissions intensify on hot days.

5. Migration and shifting

Rubber mulch can:

• Float during heavy rain

• Blow away in strong winds

• Shift during snowmelt

Requires edging to stay in place.

6. Difficult to remove

Once installed:

• Rubber mulch mixes with soil

• Cannot be composted

• Is hard and costly to dispose of

Many landscapers consider removal one of the most difficult cleanup tasks.

Is Rubber Mulch Safe for Plants, Pets, and the Environment?

Plants

Rubber mulch is acceptable for non-growing areas like tree rings and paths. But it's not ideal for:

• Vegetable gardens

• Perennial beds

• Pollinator gardens

High zinc levels and poor soil health make it unsuitable for growth-focused areas.

Pets

Generally non-toxic once cured, but:

• Presents a choking hazard

• Can stick to fur and be tracked indoors

Not recommended for heavy pet-use areas unless well-contained.

Environment

While it reuses waste tires, long-term concerns include:

• Microplastic generation

• Soil contamination

Even certified recycled products carry these risks.

Rubber Mulch vs. Organic Mulch

When comparing rubber mulch and organic mulch, the differences are significant. Rubber mulch lasts much longer—typically 8 to 10 years, while organic mulch breaks down within 1 to 2 years. However, organic mulch improves soil health over time by adding nutrients and enhancing soil structure, whereas rubber mulch provides no benefits to soil biology. Rubber mulch offers strong weed control, but organic mulch provides only moderate suppression while contributing to overall plant health. In terms of water retention, organic mulch performs better, holding moisture in the soil more effectively, while rubber mulch offers only medium retention. 

Rubber mulch also absorbs more heat, which can stress plants in hot climates, whereas organic mulch has moderate heat absorption. The upfront cost of rubber mulch is higher, but organic mulch tends to be more affordable overall. Environmentally, rubber mulch has a mixed impact due to concerns about chemical leaching and microplastics, while organic mulch provides a positive environmental benefit by naturally decomposing. For practical use, rubber mulch works best for playgrounds, pathways, and decorative beds, while organic mulch is a better choice for vegetable gardens, flower beds, and tree rings, where soil health and moisture retention are priorities.

Best Uses for Rubber Mulch in Denver

1. Playgrounds

• Shock-absorbing

• Splinter-free

• Dries quickly

2. Tree rings and borders

• Great weed suppression

• Pest-resistant

• Minimal maintenance

Leave 6 inches of space around trunks.

3. Dog runs

• Easy to clean

• No mud

• Cushioned surface

Monitor dogs who tend to chew.

4. Decorative beds

• Color options

• Softer alternative to rock

• Low maintenance

5. Commercial properties

• Long-lasting

• Reduces maintenance costs

• Clean, professional look

Conclusion

So, is rubber mulch good for your garden?
It has valuable uses, especially for playgrounds, paths, and decorative spaces. But for living garden areas, organic mulch is almost always the better option—offering soil health, plant vigor, and environmental benefits that rubber mulch cannot match.

For Denver homeowners focused on sustainability and long-term plant health, organic mulch or mineral mulches like bark, compost, or crushed granite deliver better results.

Professional Mulching Services in Denver

Mile High Lifescape proudly serves the Denver Metro area as a trusted landscape company offering:

• Expert mulching installation

• Full-service landscaping

• Lawn care and maintenance

We’re committed to transforming your outdoor space into a beautiful, thriving landscape.

Contact us: (303) 877-9091
Email: hello@milehighlifescape.com