A Complete Guide to Garden Mulching

Mulch is one of the most important tools in gardening and landscaping, yet many people aren’t sure exactly what it is or how to use it effectively. If you’re wondering what is mulch, what it’s made from, and the best options for your plants, this guide will cover everything you need to know.

What is Mulching in Gardening?

Mulching is the process of covering the soil with a layer of material—known as mulch—to protect and improve it. Mulch helps retain moisture, suppress weeds, regulate soil temperature, and even add nutrients as it breaks down. It’s commonly used around flower beds, borders, trees, and shrubs to create a neat, finished look while also benefiting the soil. They can be applied to bare soil, around plants, or to cover the surface of compost in containers. Common organic materials used as a mulch include compost, leaf mould, wood chips, bark, straw, and grass clippings. Alternatively, there are various types of decorative gravels and slates available to use as a mulch. Whatever your choice of covering, they  all serving the same valuable purpose, which is to reduce the need for weeding in the garden. In addition, using mulch helps to preserve water, deters some pests, protects the roots of plants from extreme temperatures and gives a decorative finish.

What is Mulch Made Of?

Mulch can be made from a wide range of organic and inorganic materials. The most common types of garden mulch include:

• Organic mulch: bark chippings, wood chips, compost, straw, leaf mould, grass clippings.

• Inorganic mulch: decorative stones, slate, gravel, or landscaping fabric.

Organic mulches improve soil quality over time as they decompose, while inorganic mulches are long-lasting and low-maintenance.

Is Mulch the Same as Compost?

No—it is not the same as compost. Compost is a soil improver, rich in nutrients and designed to be dug into the soil to feed plants. Mulch, on the other hand, is used as a protective top layer. While compost can sometimes be used as mulch, their primary purposes are different.

Is Mulch the Same as Bark Chippings?

Not quite. Bark chippings are just one type. Mulch is a broader term that includes bark, wood chips, leaf mould, straw, and even gravel. Bark chippings are especially popular in garden design for their natural look and weed-suppressing properties.

What is the Best Mulch to Use?

The best garden mulch depends on your goals:

• For flower beds and borders: bark chippings or wood chips look attractive and break down slowly.

• For vegetable gardens: straw, grass clippings, or compost work well to enrich the soil.

• For pathways or decorative areas: slate or gravel offer durability and a clean finish.

• Over the years, I’ve tried all sorts of materials.  All the organic mulches I have used and have been beneficial to the soil but I’ve  found the best one to be well rotted bark, that’s the very fine sort, not fresh. Bark breaks down gradually to release nutrients into the soil and help improve its structure. It will need replacing when it has fully rotted down and the key is to apply a really thick layer. An 80L bag will cover an area of about 1 meter. Last year I tried using Strulch, as a mulch.  Strulch ® is a light and easy to use garden mulch made from wheat straw for organic gardening. It worked but it did get blown about when I applied it on a particularly windy day. I used it under strawberries, and it worked well to keep the slugs at bay. However, it did break down into the soil very quickly so I’ll need to top it up this year again. 

Can I Use Multi-Purpose Compost as a Mulch?

Yes, multi-purpose compost can be used, but it’s not always the best choice. Because compost is fine and nutrient-rich, weeds can sometimes grow through it. It’s better used as a soil improver beneath a coarser mulch such as bark or wood chips.

How Do You Make Mulch?

You can easily make your own garden mulch at home:

• Shred fallen leaves into leaf mould.

• Collect grass clippings after mowing.

• Chip branches and prunings into wood chips.

• Recycle kitchen scraps and garden waste into compost for use as a light mulch.

Homemade mulches are cost-effective and environmentally friendly.

What are the Disadvantages of Mulching?

While mulching has many benefits, there are a few drawbacks:

• Over-mulching can suffocate plant roots. One significant disadvantage is the potential for over-mulching, where an excessive layer of mulch is applied around plants. This can impede water penetration, leading to water-logging, root rot, and other moisture-related issues.

   Overly thick layers can also create a haven for pests and rodents, introducing the risk of increased pest-related challenges. Improper mulching practices, such as piling it against the base of trees or plants, commonly known as “volcano mulching,” pose a risk of stem and trunk rot.  

• Some mulches (like fresh grass clippings) may encourage weeds. If you use fresh grass clippings as a mulch they might sprout as grass, but this isn’t usually a terrible probelm to fix.

• Poorly composted organic matter can attract pests.

• Inorganic substances won’t improve soil quality.

Choosing the right type and applying the correct depth (5–7cm for organic) avoids most issues.

What is the Best Homemade Mulch?

This depends on your garden. Leaf mould is excellent for borders, grass clippings work well around vegetables, and wood chips from garden prunings are long-lasting for paths and beds. A mix of organic materials often gives the best results.

Does Mulch Turn Into Soil?

Yes, organic mulch eventually decomposes and turns into rich, dark soil. This process adds nutrients and improves soil structure, which is why mulching is such a valuable gardening practice. Inorganic toppings, however, do not break down. For more ideas on how to improve the quality of your soil, read our article here.

What is the best time of year to apply mulch?

Before dormant plants have properly emerged from their winter slumber is the best time to apply a topping to the borders, working it around the spring bulbs. A perfect way to start the new gardening year.

Using weed suppressing fabric.

It was common practice some years ago to place weed suppressing fabric under a mulch to help reduce the need for weeding. However, whilst it is true that using landscaping fabric does help with garden maintenance, it is not easy to get to the soil once the fabric is in place, so adding organic matter is difficult. Beautiful gardens need good soil and one of the best ways to improve soil is adding organic matter as an annual job. In my garden I add home-made compost and well-rotted manure topped with a thick layer of bark every year as a winter task.

This might be the year for you to consider becoming a garden mulcher! It is one of the best things you can do to improve the health of your garden, and, if you get creative, it can be got for free.