Gardeners are often uncertain about the difference between compost and mulch. Compost is what remains once plant and vegetable matter has decomposed; and it is used mostly in the preparation of garden beds to improve the structure of the soil.

Because of its excellent texture, compost is invaluable for binding light, sandy soils that drain too quickly or for breaking open heavy clay soils that refuse to drain.

The term ‘mulch’ is used in two ways, both to describe the action of mulching and the medium used in the process. Mulching involves covering bare earth with any one of a number of suitable mediums to protect the soil from heat, wind, cold and frost and regulate its temperature. Compost is an excellent mulching medium.

Vulnerable Soil

The key to any successful garden is a healthy, well-draining soil. While initial soil preparation is critical, one needs to constantly maintain its good condition. Soil is extremely vulnerable to a number of climatic factors.

  • Heat is the first one to consider. Moisture evaporates rapidly from bare earth under high temperatures, and must be replaced. This cannot be considered ‘water-wise’ gardening.
  • Wind removes an unbelievable amount of topsoil from exposed soil. Observe a building site on a windy day and see just how quickly wind shifts the soil.
  • Gardeners in areas susceptible to frost will tell you just how icy cold and unmanageable the soil becomes in winter.

All of these conditions can be better managed by mulching the soil regularly.

What can I use as a Mulch?

A variety of materials are suitable for mulching. As nature intended it, there is no finer mulch than the leaves that fall naturally from overhanging trees. When left to decompose on the ground, a protective layer forms and is the finest insulator of all. Plus, ground-feeding birds will forage in this leaf litter for grubs and other insects.

Popular organic mulches include compost, macadamia nut shells, peanut shells, bark chips or wood chips, pine needles, dried lawn clippings, peach pips, straw, leaves, and even paper or cardboard.

Other inorganic materials include gravel, decorative pebbles, river boulders and even landscape fabric.

How do I Mulch the Soil?

Apply a generous layer (5cm or more) of mulch to bare soil throughout the garden. As the intention is to form a protective layer, do not dig the mulch into the soil. Remove excess mulch from around the stems of young plants to prevent possible stem-rot. Over time, earthworms and other organisms will work the mulch into the soil.

When should Mulch be Applied?

Mulch should be replenished whenever necessary and it can be applied at any time of the year. In an established garden, however, it is good practice to mulch the beds twice a year – first in spring as the weather warms, and again in autumn before it gets too cold. Mulch acts as an insulator, keeping the soil cool during the hot summer months and warm in winter.

Consider mulching not as a chore but rather as a precious gift to your garden. Over time, you will be delighted by the steady improvement in both the condition of the soil and your plants.

The Gardener