Tuesday, January 22, 2008

What's the right mulch to use?

In Perth for some reason there are people who promote the use of black mulch for their amenity gardens. This is not the recommended waterwise practice. It is better to use a chunky mulch, such as pine bark, which allows water to quickly soak through to the soil below. Many of the dark, fine mulches actually absorb the water. Not only this but I believe the dark colour is not going to keep the mulch as cool as a lighter coloured low-density mulch like chunky woodchips. Even pebbles would work well, having the added benefit of condensing water from the air in the wee hours of the morning, providing a little water in dry environments. However, many of these pebbles are sourced in a very unsustainable manner.
Vegetable gardens are treated differently as they use mulch more quickly, receiving more regular water. For vegetables use a layer of weed-free straw or hay (best being lucerne or pea-hay) if there are large gaps between plants or sprinkle manure or mulching compost on there occasionally during the growth season. It will get broken down by the higher level of biological activity. Ideally the whole of the soil surface is covered with some small herbs or low growing veges to protect the soil surface. It depends on whether you grow veges in tidy rows or untidy clumps. Both have their merits.