Determining the "perfect" companion flowers for roses usually depends more on the gardener than the garden. After all, roses come in so many heights, hues and even plant types that it's virtually impossible to pair them with a clashing flower. Many rose growers seek companion plants to combat the pests and diseases that plague rose bushes. More aesthetically-minded gardeners look for harmonious colors, scents and foliage. Whatever approach you take, pick compatible flowers that thrive under the same growing conditions (including plenty of sun and water) that your roses prefer.
The Allium family of plants, perhaps the most famous rose-defender of all, is packed with aphid-repelling vegetables like onions and garlic. For an ornamental rose bed, however, consider using members of the flowering onion family. The round, fuzzy lilac blossoms of chives, for example, make charming companions to roses, as do all the ornamental Alliums. Several other flowers boast reputations as warriors that repel aphids and other garden pests, attract "good" bugs which in turn prey on flower-chompers, or actually sacrifice themselves as "trap crops" that attract the pests and diseases which otherwise would have attacked vulnerable rose bushes. Good rose defenders include borage, marigold, nasturtiums, sunflowers, tansy and yarrow.
Classic Rose Companions
Flowers commonly considered compatible with roses include annuals and biennials such as dianthus, lantana, gerbera daisies, common geranium, snapdragon, salvia, and petunias; bulbs like tulips and daffodils; and many perennials, including Asian lilies, Russian sage, globe thistle, black-eyed Susans and purple cone flowers.
Historically, roses and herbs make classic combinations, especially in a cottage garden. Indeed, many people consider roses, with their edible petals and hips, along with the myriad perfume and cosmetic uses, to be herbs themselves. Many flowering herbs possess the additional virtue of a bushy shape, which helps mask the "leggy" qualities of shrub roses. Plant lavender, hyssop or catmint for truly classic combinations. All three feature bluish-purple flowers on spiky branches, providing an eye-catching contrast to voluptuous rose petals. In addition, all three herbs provide pungent protection from insects. For larger rose bushes casting shade underfoot, consider lady's mantle, which sports cheerful yellow flowers and beautiful foliage.
True rose aficionados often reach beyond the classic floral scent of traditional roses, seeking varieties with hints of citrus, apple, raspberry or even wine scent notes. Consider echoing that theme when choosing compatible flowers. The lemon-scented "Chrysler Imperial" rose, for example, might rub elbows with citrus-y bee balm, or any of the dozens of scented geranium varieties which also have lemon or citrus scents. In fact, scented geraniums top even roses when it comes to scent variety, so if you find an unusual scented rose, chances are a scented geranium flower exists to extend the theme. Roses which carry hints of iris, nasturtium or violet scents, of course, make intriguing choices when paired with those very flowers. Apple-scented roses work well with other flowers that carry apple notes, such as low-growing chamomile. It might strike your fancy to pair the licorice-scented "Julia Child" rose with the spicy scent of carnations.