Applying mulch is one of the best things you can do for your flower and plant beds, trees and vegetable gardens. Mulch is a layer of material, most often wood or rubber, that is spread on top of the soil to protect against erosion and conserve moisture. Mulch has many benefits, but the main reason people use it is to boost their curb appeal and put the finishing touch on their landscaping. Additional benefits include helping plants maintain a more even soil temperature, slow evaporation rates during hot summer days, and prevent weed growth to reduce garden maintenance. Garden soils and mulches should be applied at a 3-inch depth. Therefore, six 1-cubic foot bags will cover 24 square feet. For best results, keep the mulch away from direct contact with the stems of plants and trees to prevent rot and unwanted pests. Do not exceed the 3-inch depth as higher levels may prevent the roots from growing through the mulch to find water and nutrients. There are also varying types of wood chips and tree bark nuggets that can be purchased, including pine, cedar, cypress and other hardwood mixes. Colored mulch also adds another finishing touch to your landscaping with red, brown and black being the most popular choices. Gravel is permeable, allowing adequate drainage for precipitation, yet harder and more aesthetically pleasing than exposed soil. Still, there are many types of gravel, and not all are suitable for landscaping. The best landscaping gravel varies based on the area of landscaping that it covers. Surrounding a lawn or landscape, the edging frames the yard, providing a barrier between the landscape and outside traffic. Whether trailing through a garden or providing a walkway to the front door, covering the entire landscape with gravel, or using it as the primary surface, can reduce water consumption and general yard maintenance. Larger pieces of gravel, 3/4-inch and up, are best in this instance; they provide adequate drainage for rainwater and are more visually appealing than smaller rock. Large gravel rocks come in a variety of colors and materials, from jagged lava rock to soft and rounded pea gravel.ravel walkways must stand up to foot traffic.