Mulching is a common practice in garden maintenance involving the covering of exposed soil with a loose material to provide weed control, moisture retention, and temperature regulation. Most often the mulch material is also organic matter which also helps raise the nutrient content of the soil, but in some cases stone or even synthetic mulches are used to provide longer-term cover. Organic matter is sometimes also raked over lawns, which is referred to as "top-dressing". In some situations, mulches are also added on top of a soil barrier, in order to smother weeds or stabilize soil.
Mulches can be applied at any time of year. They come in a variety of colors such as red, brown, and black. In most gardens, it is only applied once in the springtime as part of the spring cleanup process, but in intensive vegetable gardens and many organic gardens, it is applied more than once. Whenever they are applied, it is always after a garden has been well-weeded and edged.
When applying mulch, it's best to start applying at the back of the garden, or in the middle in the case of "island" beds, in order to avoid walking on or rolling wheelbarrows over the mulch that's already been applied.
In gardens with large open spaces between plants, the simplest method is to simply dump the wheelbarrows or bags on the soil, then spread with a rake. In densely planted gardens, it is best to mulch by hand.
The depth of the mulch depends on the type of mulch used: for wood mulches (the most common type in most areas due to price and availability), the mulch is generally laid 1.5" to 2" thick.
Mulches should never be thrown on top of plant crowns, as this creates conditions conducive to rot. The mulch should be kept about 2" from any plant crown or tree trunk (it should never be piled up in "volcanoes" against the trunk of a tree).