The magic of mulch

Why is mulch important for your garden and what types of mulches work best? We tell you everything you need to know about mulch!

Mulch is any substance that can be placed on the surface of the soil around plants in order to keep moisture in the soil. Mulch is one of the quickest, easiest and most cost-effective ways to save water in your garden. There are two sorts of mulch – organic and inorganic.

Autumn leaves

Peach pips

Organic mulches

These come from plant and animal sources. Examples are compost, grass cuttings, pine needles, bark chips, bark nuggets, straw (not hay as there are too many weed seeds), strawy manure, crushed mealie cobs, fruit pips, nut shells, autumn leaves and shredded newspaper. Organic mulches are the best sort of mulch because, in time, they break down and enrich the soil. Earthworms help organic mulches to break down.

Inorganic mulches

These are substances or materials that do not break down and enrich the soil, but nevertheless help keep moisture in the soil. Examples are gravel, pebbles and stones.

Pine bark chips

Bark chips


What does mulch do?

  • Mulch lowers the temperature of the soil, so less water is lost to evaporation.
  • It reduces exposure to wind, which results in less moisture loss through evaporation.
  • It promotes good root growth by retaining moisture in the root zone.
  • It suppresses weed growth by keeping out the light.
  • It prevents soil being washed away from around plants during heavy rainstorms by softening the impact of the falling water and slowing it down so that it can soak into the soil before running off.
  • It functions as winter protection in cold climates, preventing frost damage to plant roots.
  • It requires no watering whereas ground covers and lawn do. All water is therefore available for nearby plants. In dry regions a mulched area around trees and large shrubs is more practical and water wise than lawn or ground covers.
  • Organic mulch eventually breaks down and improves the quality and water-holding capacity of soil near the surface.
  • Organic mulches attract useful micro-organisms and earthworms.
  • Soils with organic mulch do not need digging, as micro-organisms do all the work.

Pine shavings


How to mulch?

  • Before applying mulch, hoe the ground lightly to improve ventilation.
  • Sandy soils need a thicker layer of mulch than clay soils.
  • Make the mulch thicker during very dry, hot or cold weather.
  • Never mulch in beds planted up with seeds, which need light and oxygen to germinate. Only mulch the soil after the seeds have grown.
  • In spring, after the last frost, pull back mulch from emerging bulbs and perennials.
  • Leave a space between the mulch and the trunks and stems of trees and shrubs.


Living mulches

Low-growing, ground covering plants can also be used as a mulch. Choose shade tolerant plants for shady areas, sun-loving plants for hot, sunny places, and plants that tolerate partial shade for semi-shaded areas. For the greatest conservation of water, select low water usage ground covers. Some examples are:

For sun

Aptenia, vygies, echeveria, erigeron daisy, gazania, dymondia, trailing osteospermum, wild garlic.

For shade

Agapanthus, hen-and-chicken, variegated plectranthus.


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