One of the best ways a gardener can increase their success while also decreasing the amount of time spent watering and weeding is through the application of mulch. When applied correctly, mulch prevents water loss from the soil by evaporation, reduces weed growth, prevents weed germination, keeps the soil cooler, prevents soil splashing which in turn prevents soil-borne diseases, and improves soil structure.
Mulch can be applied at any time of the year to flower beds, trees, and shrubs. Wood or bark chips are often the mulch of choice for these areas. Shredded wood or bark is attractive and slow to decompose. Some, such as cedar, also deter insects. When applying mulch to the landscape, I always layer either corrugated cardboard or several sheets of newspaper between the soil and the mulch. This helps to choke out weeds, but has the advantage of decomposing over time which allows for my perennials and shrubs to spread.
Vegetable garden mulches should be applied after the soil has warmed in the spring. The minimum soil temperature most cool season plants require is 55 degrees F. Warm season crops, such as tomatoes and peppers prefer soil temperatures in the 70s. Mulches insulate the soil. If applied too early, the soil will take longer to warm. Soil temperatures can be more important in determining seed germination and plant growth than air temperatures. If applied after the soil has warmed, the insulating effect of mulches will maintain a uniform soil temperature, buffer the vegetable's roots from extreme heat and cool periods.
While many people use wood chips to mulch their perennial beds, shrub beds, and trees, it is not the best choice for vegetable gardens. While they do provide good weed control, wood chips have two disadvantages in the vegetable garden. Wood chips take more than one season to break down and during the decomposition process they rob soil of nitrogen. The most common vegetable garden mulches include hay and straw, leaves, and grass clippings.