Is Mulch the Best Ground Cover for a Rose Garden?

Some rose plants have bicolor flowers.

Growing roses (Rosa spp.) in a home garden can be a fun project that rewards the gardener with exquisite, fragrant flowers. Roses can grow in U.S. Department of Agriculture plant hardiness zones 4 through 10, depending on the variety, and are not difficult to grow when given the correct conditions. Using a mulch under rose plants helps fulfill some of their requirements for good growth, but you can also use certain plants as a groundcover to add additional interest to your rose garden.

Conserving Moisture

A mulch is a material added on top of the soil under a rose bush and can include organic mulches, such as shredded bark, wood shavings, straw, hay and pine needles. Mulching with a 2- to 3-inch thick layer of these materials mulch under the plants provides several benefits. Roses need about 1 inch of water during the growing season and one of the most important benefits of mulch is its ability to conserve soil moisture by keeping soil cool during hot summer months and slowing evaporation from its surface. As the season progresses, you should renew mulch as it decomposes, especially during dry spells when soil tends to dry out quickly. Inorganic mulches such as shredded rubber are also available, but these aren't good choices for roses because they can slow movement of water into the soil and, once the soil does become wet, it can stay wet for long periods.

Fertilizing for Blooms

Applying and maintaining a layer of mulch under roses also helps keep down weeds that compete for water and soil nutrients. But as it decomposes, organic mulch binds nitrogen in the soil, so you should compensate for this by fertilizing the plants. A general purpose fertilizer such as a 10-10-10 granular formula works well, applied in spring at a rate of about 1/2 cup per plant. Spread fertilizer in an 8-inch-wide, circular band about 6 inches from the plant's center, mixing it into the soil and watering lightly after application. A second feeding in early summer helps keep plants blooming, but avoid feeding in late summer so that new, easily damaged growth doesn't appear when weather turns cool in late fall.

Preventing Disease

Although mulch has some important benefits for roses, it can make the plants more susceptible to fungus by keeping air under the plant moist. Fungal disorders such as root rot, powdery mildew and black spot can seriously damage roses if not checked. You can help prevent these problems by keeping a 6-inch-wide circle under the plant's center free of mulch, moving it away from this area when wind or rain redistributes it. Choosing pine needles as mulch can also help prevent disease because the needles help keep water from splashing on the plants during rain. You can also help prevent spread of fungal spores, which can overwinter in mulch, by replacing the layer with fresh material each spring.

A Living Ground Cover

Although mulch has several benefits as a ground cover, you could also use low-growing plants as a living ground cover. Choose plants with growing requirements similar to those for roses. Examples include spring-to-summer blooming perennials such as hardy geraniums (Geranium sanguineum), also called cranesbill, which have pink flowers and grow about 1 foot tall in USDA zones 4 through 8, and Serbian bellflower (Campanula poscharskyana), which grows in zones 3 through 8, is about 1/2 to 1 foot in height and has lavender-blue flowers. You could also under-plant roses with low-growing annuals, such as pansies (Viola x wittrockiana), which can survive winters and grow as perennials in zones 6 through 10.

About the Author

Joanne Marie began writing professionally in 1981. Her work has appeared in health, medical and scientific publications such as Endocrinology and Journal of Cell Biology. She has also published in hobbyist offerings such as The Hobstarand The Bagpiper. Marie is a certified master gardener and has a Ph.D. in anatomy from Temple University School of Medicine.