How much do I need?
The amount of mulch depends on the size of your garden and on the thickness of mulch required.
A standard application of mulch is around 10cm (4 inches) in depth. A premium application is around 15cm (6 inches) in depth.
Calculating mulch requirements
Firstly, you’ll need to decide if you’re going to apply a standard or premium level of mulch.
Then simply enter your garden bed width and length to calculate how much mulch you’ll need.
Results are given to the nearest half a cubic metre.
A little bit about mulch
Mulch protects plants and trees from weeds, moisture loss and temperature damage. It must be applied at the correct depth around the plants or the benefits are minimal. Mulch can harm plants when applied too deeply by causing too much moisture to build up and inhibiting aeration to the soil beneath. The correct depth depends on the mulch and the types of plants growing in the mulch bed.
Mulch for trees
Trees benefit from a mulch depth between 5-6cm (2 – 2.5 inches). The thick mulch layer suppresses weed and plant growth under the tree while retaining moisture in the soil. Thicker mulch layers may retain too much moisture and cause surface roots to suffer rot, while a thinner layer supplies few benefits. Applying the mulch at the right depth is only part of proper application. The mulch must also cover the ground over the root system and beneath the tree canopy. Leave a 5cm (2-inch) space between the mulch layer and the tree trunk. Moisture in the mulch can cause the trunk to rot.
Mulch for garden plants
Vegetable and flower gardens also benefit from a mulch application for both moisture retention and weed suppression. The mulch also helps insulate the soil so it does not freeze quickly or become too hot and damage the plant roots in the bed. Garden plants require a mulch depth near 5cm (2 inches).
Mulch in those winter months
A deep mulch depth may harm plants in summer, but a thicker layer of mulch protects the plants in winter. Increasing the depth around dormant perennial beds to 7cm (3 inches) provides insulation against winter cold.