Unlike many old-fashioned rose-only gardens, today's rose gardens often include other plants, such as complementary herbs and flowers. One valuable purpose other plants can serve in a rose garden is to form a ground cover that protects rose roots and keeps out weeds. Ideal ground covers for rose gardens are hardy, aesthetically pleasing, and do not compete with roses for either space or soil nutrients. Plants with similar growing requirements to roses are recommended.
In her book "100 Old Roses for the American Garden," rose expert Clair G. Martin suggests lemon thyme as a complementary ground cover for roses. This perennial herb forms low mats of tiny emerald leaves, which are tough enough to withstand trampling. When crushed, lemon thyme exudes a fresh, clean, citrus-like odour that harmonises with the sweet scent of rose blossoms.
Like roses, this native Mediterranean herb flourishes in full sun. It bears petite, starry white and light lavender flowers that attract honeybees and other pollinators. Lemon thyme is generally hardy in U.S. Department of Agriculture growing zones 5 to 9, a region including most of the central and southern United States.
Martin also recommends sweet alyssum (Lobularia maritima) for keeping rose roots cool in the summer and creating a natural mulch when it dies off in the winter.
Sweet alyssum is a hardy annual native to southern Europe and naturalised throughout the United States. This plant grows in a spreading pattern, reaching a maximum height of 8 to 12 inches. It is both drought tolerant and heat resistant, requiring little care. In the summer, sweet alyssum bears profuse clusters of delicate, lacy white flowers that perfume the air with a sugary fragrance. Like roses, this plant enjoys sunny conditions.
Corsican mint (Mentha requienii) is an unusual mint species well-suited to forming a natural carpet for rose gardens. Originating on the Mediterranean island of Corsica, this ground-hugging mint forms low, spreading mats and reaches maximum heights of under a foot. Its rounded, dark green leaves are notably small for a mint. Like lemon thyme, Corsican mint may be trampled underfoot, emitting a potent peppermint-pennyroyal aroma when crushed). Unlike many mint species, which tend to spread like wildfire, Corsican mint is not invasive. It can grow in full sun or partial shade, prefers slightly acidic soils, and is hardy to growing zone 5.
Another suitable ground cover for rose gardens is woolly yarrow (Achillea tomentosa), a woody, evergreen herb. Woolly yarrow reaches only an inch or two from the ground, bearing soft, feathery greyish foliage that emanates a pungent aroma. In the summer and fall, clusters of golden flowers emerge. This herb is hardy in growing zones 3 to 8. It spreads tenaciously and is capable of surviving periods of drought.