Mulch is any material placed over the surface of soil as a covering, and is often used in pathways, garden beds, or beneath perennial plants. Mulch helps to retain soil moisture, suppress weeds, and keep the soil cool – all of which benefit annual and perennial plants. Many gardeners agree that mulch also makes the garden bed look neat and beautiful.
Organic mulches are any type of decomposing organic matter that can be used as a soil covering
while
breaking down and adding nutrients to the soil. Some examples of organic mulches include shredded leaves, newspaper, straw or hay, and even cardboard. These materials provide the added benefit of improving soil structure, drainage, and nutrient-holding capacity as they decompose, while also offering the benefit of weed reduction.
When choosing an organic mulch, it’s important to think about how quickly a given material will decompose. Bark, for example, is an excellent option beneath perennials as it decomposes very slowly and can be added to each season, developing a more or less permanently mulched area. On the other hand, straw or leaves will break down sooner, typically within a season, but make a nice home for beneficial insects which will help keep the pest population in control – perfect for annual vegetable crops.
When considering quantity of organic mulch, a 2- to 3-inch layer is necessary to smother weeds and retain soil moisture. Less than 2 inches of mulch will let in enough light to allow weed seeds to germinate. When applying any kind of mulch, be sure to give your plants an inch or so of space from the mulch. When applied right up to a plant's base, organic mulch can hold in excess moisture and lead to rot.
