When placing mulch in your garden it is important to consider the texture of both the soil and the mulch. If a layer of mulch is too thick it may prevent air and water from reaching the soil. Air and water are important both to the roots of the plant and the microorganisms found within the soil. Heavy clay soils are not well aerated due to the small amount of pore space. Coarse mulch should be placed on clay soils in a layer no thicker than five centimetres. Sandy loam soils have larger pore spaces that allow for more aeration. A thicker layer of mulch with a fine texture can be added to a depth of eight centimetres.
Soil with a layer of mulch on top takes longer to warm in the spring. The layer of mulch also prevents water from evaporating. When adding mulch to a bed, wait until the soil temperature increases.
It is important not to place mulch against the base of trees, shrubs, or herbaceous plants. Mulch can provide a home for rodents that may chew on the base of plants causing severe damage and even killing the plant. Also, mulch retains moisture and heat, which will damage the base of the plant. Keep mulch 15 centimetres away from the base to prevent any problems.
Mulch decomposes as it ages; therefore it will need to be replenished from time to time. How often will depend on the type of mulch being used. Try to keep the layer five to eight centimetres thick throughout the season.
In the long run, mulching your flower and vegetable beds can save you a lot of time. It can drastically reduce the amount of time you spend weeding and watering. It also looks good and prevents soil from splashing onto your flowers when it rains.