How to choose the best mulch for your garden

Wood chips

Wood chips make excellent mulch, especially for trees and shrubs. Having fewer fine particles wood chip is very effective at allowing water infiltration. The particles can be screened to ensure a particle size of not less than 16-20 cm. Wood chip is relatively slow to decompose, making a longer lasting mulch.

Be careful where you source your wood chips. The local arborist may seem a good option but they often deal with diseased trees. Wood chip is low in nitrogen — good to suppress weeds, less useful for gross feeding crops. It is also slow to breakdown and large particles can interfere with seed bed preparation, so is not recommended for vegetable gardens.

Mulch for vegie gardens

Diggers uses organic, lucerne mulch on the kitchen gardens. It allows good water infiltration but also insulates the soil.

On the Heronswood parterre, partially for aesthetic reasons, a thin, 50mm layer of our own compost is used. This compost layer is regularly “tickled” with a small rake to suppress weeds. Other proven mulches for vegie gardens include pea straw, home-made organic compost and sugar cane.

Carpet

Carpet can function as mulch but has a few pitfalls. As a recycled manufactured product you cannot be sure what it is made out of or what chemicals it has been treated or glued with.

It can also make a snug home for rodents and other pests to tunnel under. It may prevent moisture penetration and it looks pretty bad as it breaks down.

It is perhaps best used as a weed barrier on pathways where you want nothing to grow.

Plastic

Plastic mulches of various colours are widely used in commercial vegetable production. Black plastic is most commonly used in strawberry production but its use raises some environmental concerns.

One of the most interesting aspects of plastic mulch is the use of coloured plastic to manipulate production. Tomatoes can yield earlier and more heavily when mulched with red plastic.

The plastic intensifies red light increasing plant photosynthesis. The effect of colour is still being researched with different plants and colour combinations producing quite different results.

Organic mulch for annuals in vegetable and flower gardens

Mulch for perennials, trees and shrubs