A Beginners Guide to Mulching

colourful shrubs kept healthy through mulching Many people use mulching to save time on garden maintenance. While pro gardeners know a fair bit about mulch, new gardeners might find it hard to collate all the information available on it. Here’s a concise beginners guide that gives you all you need to know about mulch.

What is Mulch?

Mulch is a protective, insulating layer of organic or inorganic matter applied to the surface of soil.

Why Should You Use Mulch?

Mulching helps to reduce plant stress whenever the climatic temperature fluctuates. Incorporating mulch will help to stabilise temperature and as a result, plants will not have to work hard to adapt to changing climatic conditions. It also helps reduce the amount of moisture the ground loses through evaporation. As a result, plants do not experience water stress especially during higher temperature seasons like summer. Preserving the moisture will also help reduce the need for irrigation – saving you some time and effort. Mulching also contributes to controlling weeds that might affect your plants. When you apply a thick enough layer of mulch it will block most of the air from reaching it. Weeds that are growing will be suffocated since they can’t access adequate oxygen. Organic mulch has the potential to improve the ground’s nutrient profile. When the organic material breaks down it decomposes and finally mixes with the earth adding nutrients to it. Mulching also plays a part in curbing erosion. When you overlay the ground with mulch it covers it and forms a cover that acts against erosion when it rains. If you want to curb erosion in areas experiencing high winds or located along steep slopes you need to use heavier mulch. It will be harder to shift through natural environmental movement or strong wind.

When is Mulch Applied?

You can add mulch to your garden at any time. However, there are particular times that are more favourable than others:
  • You can mulch your garden in the spring. Applying mulch at this time will help retain a good portion of the moisture in the earth from the wet season. In summer this retained moisture will carry your plants through the drier season.
  • Layering the ground with mulch in autumn after routine major garden maintenance will help keep weeds from proliferating in the autumn through to spring.
  • You can also add mulch (a thick layer of it) during winter, but you need to do this during the early part of the season. It will protect the roots and shoots of the plants (especially vulnerable ones) from the frost and other wet weather vagaries. 
When you decide to apply mulch ensure that you do a round of thorough weeding first.

How to Apply the Mulch

  • Prepare the soil: The first thing to do when preparing your garden for mulching is to remove any weeds from the ground. You can spray them or pull them out (make sure you do it by the roots and not the shoots). Once you’re clear of the weeds, you can then make sure the earth is moist. Water the ground if necessary as moisture is crucial.
  • Trim any edges: If you only have a small area to work with it is advisable to create an edge using a shovel or manual edger where you will apply the mulch. If you will be adding mulch areas with trees use stones to create an edge that will stabilise the mulch.
  • Add fertiliser – If you opt for organic mulch you will need to first add a nitrogen-rich fertiliser before starting as mulching will deplete the earth of nitrogen during the breakdown process.

Other Mulching Tips

  • When adding mulch keep the thickness to 2-3 inches for the best garden care. Mulch less than two inches will not hold back the weeds from growing, while mulch that is more than three inches thick will end up preventing water from reaching the ground.
  • When using organic mulch the most optimal garden maintenance routine is to reapply it twice per annum. Biodegradable mulch breaks down quicker than other types of mulch and therefore reapplication is necessary to keep it well layered.
  • Do not place mulch around the stems or trunk of plants (including Australian flowers) to avoid triggering stem rot or stifling plant growth. Best practice in is to leave a space of about an inch between the stem and the mulch.

Types of Mulch

There are two main types of mulch popular in gardens across Sydney; organic and inorganic mulch.

Organic Mulch

Organic mulch, also known as biodegradable much, is made up of material that decomposes over time and becomes part of the earth. The main benefit of this type of mulch is the nutrients that it adds to the earth as it breaks down over time. When using organic mulch to fight weeds ensure that you layer it over ground that you have already weeded. You also need to make sure that you apply a thick enough layer to prevent regrowth of these weeds. Organic mulch is acidic and you should add some lime alongside the mulch to neutralise the impact of this acidity. Examples of materials you can use to make biodegradable mulch include leaf mould, rotten hay, seaweed, wood chippings or garden compost.

Inorganic Mulch

Inorganic mulch, also known as non-bio degradable mulch, is made up of materials that do not decompose over time. Inorganic mulch is great at repressing weeds, keeping plant roots warm and also helping retain moisture. Some of the materials that can make for inorganic mulch include sheet covers, sea shells, slate, pebbles, gravel and tumbled glass. If you decide to use plastic sheets note that you will need to confirm its permeability to avoid preventing rainwater from reaching plant roots.


Mulching has many benefits that can promote the health of your garden. There are different types of mulch with each coming with their pros and cons. Know how to best add mulch to your garden for maximum benefit.

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