Spreading a protective covering on top of the soil has many advantages for the rose gardener. In addition to giving a neat, attractive appearance to rose beds, it slows the evaporation of moisture from the soil and prevents the formation of a hard crust. Left in place all year, it insulates the soil, preventing rapid temperature changes in the soil during the winter as well as the summer.
Mulching is also invaluable in weed control. Apply a mulch around the rose plants or over a whole bed. Generally, rose gardeners use organic mulches; as the materials break down, they improve the soil.
After planting, apply 2 to 4 inches of mulch. Do not let it mound up around the base of the plants. If you have had problems with diseases, remove all the old mulch yearly in early fall and replace it with fresh mulch.