Hi @leon90,
Welcome to the Bunnings Workshop community, it is wonderful to have you with us.
Generally, you want somewhere between 30–70 mm of mulch, depending on the type you use.
There isn't really a best type generally, as the type of mulch you choose really depends on what you’re trying to achieve in your garden.
If your goal is water retention and weed suppression, go for a chunkier mulch like Richgro Pine Bark Mulch, Richgro Hard Wood Mulch. These coarser types allow good airflow, last longer, and don’t compact easily. They’re great for long-term, low-maintenance beds and for areas planted with shrubs, perennials, or natives. For these mulches, I'd suggest a layer 50mm thick.
If you’re trying to improve soil health and structure, a finer mulch such as sugar cane mulch is a good choice. These break down faster, adding organic matter to the soil and helping to build fertility over time. They are ideal for veggie patches or mixed garden beds where you replant regularly. For these lighter mulches, aim for a 70mm thick layer
For a 5 m x 5 m bed, you’ll need about 1.25 cubic metres for a 50 mm layer, or around 1.75 cubic metres for a 70 mm layer.
You can either buy mulch in bulk bags that are sold by the cubic metre or in bags that are labelled with how many litres they are. Keep in mind that 1000 litres is equal to 1 cubic metre.
Whichever type you choose, it’s important to keep the mulch a few centimetres away from plant stems and trunks to prevent rot and pest issues. Also, try to top up mulch once a year as it naturally breaks down and thins out.
Let me know if you have any further questions.
Jacob
