Mulch

What are the benefits of mulch?

• it significantly reduces evaporation of water from the soil
• it keeps the soil, and therefore the roots of the plants, cooler
• it reduces the amount of water needed for watering
• organic-based mulch can improve the soil structure, in the long term

What kind of mulch:

I prefer organic-based mulches over pebbles or gravel, as they improve the soil as they break down. Pea straw and lucerne are good, as are mulches based on bark.  The latter are available commercially and also, quite cheaply, from the Adelaide City Council, which accepts green waste and turns it into compost and mulch for sale to ratepayers and the general public.

What to avoid:

• thick layers of freshly cut grass
• thick layers of autumn leaves

Both tend to form matted clumps that prevent water getting through to the soil

• sawdust.  This tends to cause ‘nitrogen drawdown’ leading to a nitrogen deficiency in the soil

How thick ?

The thickness of the mulch depends on how fine the material is. If fairly coarse, you will want a layer approximately 4 – 5 centimetres thick. If you are worried that the mulch is too thick, lift up and check underneath after watering.

When to apply

Apply in mid-spring when the soil had had the chance to warm up. Wet the soil thoroughly before laying.