Organic mulches are the best to use in your landscape. Native hardwood mulches are readily available from the municipal recycling programs and also many retailers. These hardwood mulches will break down to act as a natural fertilizer to your plants. Mulches also discourage weeds, cool the soil temperature, protect from erosion and conserve water. Mulch should be kept at a 3 inch depth and can be applied anytime of the year. The most common time is in the spring. The depth of the mulch should be checked in the fall as well.