Choose the material for the job
The Australian Native Plants Society Canberra Region’s mulching guide distinguishes organic materials that break down from inorganic materials such as gravel. Those materials do different jobs, so appearance alone should not decide the choice.
Before ordering, tell the supplier what is growing in the bed, whether the position is exposed or sheltered and what material is already there. Ask about the suitable finished depth for that product and planting.
A decorative gravel surface and a vegetable bed are different situations. If you have native plants, ask for advice suited to those species. Avoid treating “organic” as a promise that every product suits every plant.
Prepare a small area properly
Identify the plants you want to keep and the weeds you intend to remove. Move loose rubbish out of the bed and make sure irrigation fittings will remain accessible. Photograph anything unfamiliar rather than covering it and hoping it will disappear.
Measure the existing mulch depth at several points. A top-up needs to account for what is already on the bed; adding a full new layer every time can produce an unexpectedly deep build-up.
Choose a place for the delivery that leaves doors, gates, drains and paths accessible. If you are booking help, say whether material is already on site and describe any steps or narrow access.
Calculate the volume before ordering
For a rectangular bed, multiply its length by its width to get the area. Then multiply by the additional depth you plan to add, with all measurements in metres.
Worked example
A 4 m × 2 m bed covers 8 m². If the appropriate additional layer is 50 mm, convert that to 0.05 m: 8 × 0.05 = 0.4 m³, or 400 litres. That is ten 40-litre bags before any allowance for the shape of the bed or material settling.
The 50 mm depth is an arithmetic example, not a recommendation for every mulch. Confirm the required depth before using the calculation.
For an irregular bed, divide it into smaller shapes you can measure and add the areas. Subtract substantial spaces you will leave unmulched. Ask the supplier to help check a large order.
Spread evenly and leave stems clear
ACT Climate Choices’ garden-water guidance recommends keeping mulch away from plant stems. Spread to the agreed depth and check around plants as you go rather than leaving the detail until the load is empty.
Keep paths usable and irrigation components accessible. After watering or rain, check whether water is reaching the soil instead of assuming the surface appearance tells the whole story.
Record the material and the amount applied. That gives you a starting point when you next inspect or top up the bed, and helps a gardener understand what has already been done.
Before you book a mulch job
Ask whether the quote includes weeding, supply, delivery, spreading and removal of leftover bags or waste. Describe the garden beds and the route from the unloading area. A clear scope makes quotes easier to understand.
Does mulch remove the need to weed? No. It can help suppress weed growth, but you still need to inspect the bed and remove weeds that appear. Identify them before choosing how to manage them.
Should I add the same depth every year? Measure what remains and check the guidance for the material. Treat a top-up as a measured job, not an automatic new layer.
A practical checklist
0 of 5 complete
Sources & further reading
ACT Climate Choices: mulch and garden water
General gardening guidance. Check plant-specific advice and current conditions before acting. Planning examples and checklists are our editorial suggestions.