Mulching involves covering the soil with an orgainic material such as peat, bark, coir or cocoa shell. This cover keeps weeds down and when the mulching material eventually breaks down it goes in to the soil, providing Humus.

Peat:
Peat has been the most common mulch for a very long time.
Peat is still the most widely used source of Humus in Gardening.
However it is to all intents and purposes a non-renewable material and we now need to preserve it by changing to peat alternatives. As a mulch it can look untidy compared to Chipped Bark

Bark:
Bark is the best alternative to Peat and as it is a waste product from forestry it is environmentally friendly.
Chipped Bark is an ideal mulch and is more decorative than composted bark or peat.
Bark is in fact superior to peat in that it is slower to break down and so lasts about 3 times longer than peat.
Ground or Composted Bark is an ideal alternative to peat for digging into the soil to raise the humus level or as a mulch. Like Peat it can look untidy as a mulch compared to Bark Chips.

Cocoa Shell:
This was a popular mulch for a while but the cocoa tends to attract mice.

Coir:
This was a popular mulch for a while but has lost popularity. Many considered its export too damaging to the environment and economy of the islands where it came from.