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To Mulch or Not to Mulch: Pros & Cons

Ever wondered what the fuss about mulching is all about? Is it a gardening magic bullet or simply an overrated practice? As with most things in life, the answer isn’t straightforward. The choice of whether to mulch or not depends on a variety of factors and understanding the pros and cons can help you make an informed decision.

If you do choose to mulch, there are some best practices to follow for optimum results.

To Mulch or Not to Mulch Pros & Cons
This mulch is varied with different chip sizes and plenty of fine particles

What is Mulching?

Definition and Description

Mulching, at its core, is the practice of covering the soil around plants with a layer of material. This material, known as mulch, can be either organic, such as compost, straw or bark chips, or inorganic, like gravel or black plastic. Each type of mulch has its own set of benefits and drawbacks, and the choice largely depends on the specific needs of your garden.

The Science of Mulching

Mulching works by creating a protective barrier between the soil and the atmosphere. This barrier serves multiple purposes: it helps retain soil moisture, regulate soil temperature, suppress weed growth, and improve soil health. Mulch also adds an aesthetic touch to your garden.

To Mulch: The Pros

Soil Health Improvement

One of the primary benefits of mulching is improved soil health. Organic mulch, in particular, decomposes over time, adding valuable nutrients to the soil and improving its structure. This process promotes beneficial microbial activity, leading to healthier, more fertile soil. A study by the University of Illinois Extension demonstrates that mulched soil tends to have higher nutrient content and better structure than unmulched soil.

Weed Control

Mulching is an effective tool for weed control. By blocking sunlight, mulch prevents weed seeds from germinating, thus reducing the need for tedious weeding. According to research published in the journal Weed Science, organic mulches can reduce weed growth by up to 80%.

Water Conservation

Mulch plays a crucial role in water conservation. It slows evaporation, allowing soil to retain moisture for longer periods. This means less frequent watering, which is both time-efficient and environmentally friendly.

Soil Carbon

As organic mulch breaks down, it releases carbon into the soil. Soil carbon is beneficial as it improves soil structure, promotes nutrient uptake by plants, and enhances the soil’s water-holding capacity. It’s important to note that soil carbon is different from nutrients like nitrogen, phosphorus, and potassium (NPK) and micronutrients, which are essential for plant growth but don’t contribute to soil structure or water retention.

Not to Mulch: The Cons

Potential Pest Issues

While mulch can enhance soil health and plant growth, it can also create a favourable environment for pests. Mulch provides shelter and food for some organisms, which, unfortunately, includes pests like slugs and rodents. However, these issues can be mitigated by using pest-resistant types of mulch and regular garden inspections.

Possible Fungal Diseases

Mulch can sometimes harbour fungal diseases, especially when it’s piled too high around the stems of plants, creating a damp environment. To prevent this, ensure you apply mulch correctly, keeping it away from plant stems.


Certain types of mulch, especially those with high carbon content, low nitrogen levels, and fine particles, can become hydrophobic, repelling water instead of retaining it. This can prevent moisture from reaching the root zone of your plants. To avoid this issue, consider using coarser types of mulch and mixing different types together.


While mulching has many benefits, it’s important to remember that some beneficial organisms, such as solitary bees, require uncovered soil to build their nests. Therefore, leaving some areas of your garden unmulched can support local biodiversity.

Cost and Time

Mulching requires an investment of both time and money. The cost of mulch varies depending on the type, and applying it is a labour-intensive process.

Guidelines for Effective Mulching

Choosing the Right Mulch

When choosing a type of mulch, consider factors like your garden’s needs, the local climate, and your budget. For instance, organic mulches improve soil health but need to be replaced regularly, while inorganic mulches last longer but don’t enrich the soil.

Best Practices in Mulching

For effective mulching, apply a 2-3 inch layer of mulch around your plants, keeping it a few inches away from plant stems to prevent fungal diseases. Also, remember to water your soil before applying mulch to ensure it’s moist.

Daniel’s Wrap

The decision to mulch or not to mulch depends on various factors, including your garden’s specific needs, your time, and budget. While mulching offers numerous benefits like improved soil health and weed control, it also has potential drawbacks like pest issues and cost.

Therefore, weigh these pros and cons carefully before deciding, and should you choose to mulch, follow best practices for the best results. Remember, informed gardening practices are key to a healthy, thriving garden.

Daniel is a writer and content creator for Ozbreed, one of Australia's leading native and exotic plant breeders.

Daniel has worked in various capacities within the horticulture industry. His roles have ranged from team leader at several companies, to creator of the Plants Grow Here podcast and Hort People job board, as well as his position on the National Council for the Australian Institute of Horticulture (AIH).

He's passionate about explaining how to care for different types of plants to ensure home gardeners and professional horticulturists alike can get the most out of the plant babies.

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