Which Mulch Is Best For Australian Gardens?

Luke Smith June 14, 2022

How we rank these mulches

There are actually real world, practical differences in the common mulch varieties used in Australia gardens. In this article, I am going to rank eight popular mulch options, using four different categories.

1. Longevity: How long does the mulch hold its colour and appearance compared to other mulches?
2. Soil Moisture Retention: How well does the mulch help the soil retain water? The larger the particles/chips in the mulch, the better it is at retaining moisture (read here for more). For example, large particles like wood chips allow water to flow through freely to the soil, whereas smaller particles like grass clippings can absorb a lot of the water before it gets to the soil.
3. Soil Improvement: How much does this mulch help improve soil quality over time? All mulches are beneficial for the soil but some have increased beneficial effects.
4. Price Guide: How expensive is the mulch? This is a guide only as prices can fluctuate. Call your local supplier for a proper quote.

Please note: These rating are our opinions based on our experience having completed gardening services at thousands of locations throughout the suburbs of Perth, Western Australia. In addition, different mulch suppliers may have different levels of quality when comparing equivalent products, so take these ratings as a general guide.

Our Rankings In A Nutshell

Made with Karri (and sometimes Jarrah) bark mixed with peat, Karri and Peat is the king of black mulches. It is the longest lasting black mulch and the extra peat can help improve soil quality.

However, this mulch has smaller particles which do have a negative effect on soil moisture retention. If your number one goal is to help your garden become water wise, Karri and Peat is not the mulch for you.

But, if your goal is a rich, dark, long lasting colour, then this is what you are looking for.

Black mulch does vary between suppliers (which is why our ratings vary) but it is often a budget mulch, dyed black with a small amount of peat. When it is freshly installed, it looks just as good as Karri and Peat, however, that look does not last anywhere near as long.

There can be a lot of fine particles in these mulches which makes them poor at moisture retention. Overall, our opinion is that this is not a good value for money option. If a black mulch is what you are looking for, in our experience, Karri and Peat is a better value for money option.

In my opinion, pine bark mulch is the best wood chip style mulch. Like other wood chip mulches, it has a large particle size which is great for moisture retention. In addition, it holds its colour better than any other mulch.

Whilst the price at face value seems expensive, it is actually very good value for money when you consider longevity. This is a great mulch for those who are looking for long term results and real moisture retention.

Wood chip mulches, are great at retaining moisture because of their large particle size. It holds colour longer than the cheap mulches but are still at a fairly affordable price. But, in the the hot Australian summers, the wood chip style mulches can turn grey quite quickly.

This is a great middle of the road option.

Red wood chip mulches are essentially the same as standard wood chips mulches that have been dyed to give a vibrant red colour. The quality of mulch used does vary between suppliers. If a wood chip mulch had been used, there will be no noticeable difference in moisture retention and soil improvement compared to other wood chip options.

The problem is that when this colour fades, the mulch can look unappealing. In addition, it is quite a bit more expensive than standard wood chips. If you love the red colour then this is not a bad mulch to buy. However, be prepared for the extra cost and to lose the colour fairly quickly.

Economy mulch (will have different names for different suppliers) is often the cheapest mulch option at the local soil supplier. It is made as a byproduct of gardening and tree lopping waste that is left to age; this gives the mulch a nice dark colour.

Whilst economical and nice to look at, the fine particles in the mulch make it less effective at retaining moisture when compared to wood chip mulches. However, there can be a significant difference between suppliers and some batches/supplies do have a nice large particle size.

The longevity of colour is not great, but better than free mulch. All things considered, we do recommend these mulches as a good option for those on a budget.

Straw mulches like hay or lupin mulch are very high in nitrogen and are some of the best mulches for water retention. This is partly due to them having no small particles and partly because straw mulch is often applied at thicker rates (10-20cm) to other mulches (5-10cm).

The down sides to straw mulches is that they are the most expensive mulches on this list. In addition, they break down quickly, which is great for adding nitrogen to the soil, but the rate of replacement plus the expensive outlay makes this an unrealistic option for large gardens. They also may contain seeds from the plant the mulch is made from.

Straw mulches are best when applied in veggie patches and other small garden beds. On a larger scale, it is not a practical option.

Free wood mulches from tree lopping businesses are a great option if you are looking to do a large area on a budget but they do come with some issues.

1. It is very common to get much more mulch than you need. Your delivery is simply a truck of waste from tree looping jobs. You can rarely ask for an exact amount.
2. The quality of the mulch is very low, often filled with small sticks and leaves which can be unsightly.
3. The mulch is very fresh, so has a lighter colour than other wood chip mulches.
4. It goes grey very quickly in the Perth sun.
5. Whilst unlikely, there is a chance that free mulch may contain diseased trees and branches. This disease may spread to your plants if they are susceptible.

Whilst free mulch is very attractive to some on a budget, each person will need to know what they are signing up for before they make an order. I only recommend this mulch for very large areas where the budget is very tight.

Please note: Silverstone Gardening does not supply or lay free wood mulches to clients as we cannot guarantee the quality of the mulch or the results of our service. Our focus is to give our clients the highest quality service possible.

So, which mulch is best for Australian gardens? It depends on what you are looking for.

So, which mulch is best for WA gardens? Well, I can’t answer that for everyone, but I hope you now have the knowledge that you need to make the right decision for your garden.

If you still have any questions about mulches, or perhaps are wanting to find out about a style of mulch not listed here, then talk to your local soil and mulch supplier. There are plenty of knowledgeable and friendly mulch suppliers who will be able to help with your requests.

If you are looking for a service that can organise and complete your mulching job from start to finish, contact Silverstone Gardening today. We have qualified and experienced gardeners who can help identify and solve problems in your lawns and gardens. Mulch installation is just one of our services.

Contact our friendly admin team for a quote.