Companions in Life - be they spouses, partners, or even pets and their masters - should be compatible to thrive in each other's company. Ideal companion plants are the same way, and two of the best are clematis and roses. Both relish large doses of water, flourish in the same location and soil, and benefit from similar fertilizing schedules. Yet for all their similarities, they complement each other perfectly.
Most clematis are climbers by nature, and because they are not self-supporting, they will happily wander up any nearby plant or support. Clematis and climbing roses can grow together up a light post, doorway, or garden wall, providing a lush vertical display of flowers as they bloom. Alternatively, guide clematis horizontally onto shrub or ground cover roses for a low-growing border.
Before pairing clematis and roses, you should know about the characteristics of each. Clematis are either large-flowered hybrids or small-flowered species and their hybrids. Most are suited to USDA Hardiness zones 3 through 9, although a few adapt to zone 10. Large-flowered hybrids have tough roots and large, rarely scented flowers, and can suffer from wilt, a fungal disease specific to clematis. Small-flowered clematis tend to have fibrous roots and a profusion of smaller flowers, which may be scented; they are rarely affected by wilt. Both groups include varieties that flower early, midseason, and late, and their pruning needs differ according to their bloom times.
Climbing, shrub, and ground cover roses can be matched with clematis. Climbing roses can flower repeatedly, producing single or double blooms that are typically scented, and they require little pruning once established. Most climbing roses need to be tied to a support, such as a trellis, pole, or wall. Shrub roses, available in many ever-blooming varieties, can stand alone and are typically hardy and low maintenance. Ground cover roses are hardy, disease resistant, and low growing.
It is possible to match almost every clematis with a rose, but the beauty of the pairing lies in the size, color, scent, and timing of their respective blooms. Among the many ever-blooming varieties of roses and clematis, it's easy to find two plants that will flower together from spring through fall.
You can also plant up to three different clematis with each rose. Choose one early-flowering variety that will bloom before the rose, another midseason kind that will bloom in unison with the rose, and a late-flowering one to bloom after the rose has finished. Such a combination will provide an abundance of color and activity lasting all season.
Both clematis and roses are available in a wide array of colors, making the possibilities almost endless. Create exciting combinations by selecting varieties in colors unique to each plant. Clematis, for instance, come in shades of blue, while roses never do, but roses display an orange color unseen in clematis.
Because small-flowered clematis are more resistant to wilt, consider them over large-flowered hybrids. Keep in mind, though, that combining C. montana with roses is not recommended. It is the most vigorous clematis and so tends to overwhelm a shrub rose and may even damage climbing roses. Nevertheless, C. montana adapts well to warm climates; if you decide to use it, be sure to plant compact varieties like C. m. 'Freda' and C. m.Peveril', combining them with large shrub roses that can compete with their exuberance.
Robust companions. As you decide on pairings, be aware of the plants' growth habits. For instance, C. viticella is a robust, easy-care species that yields a profusion of small flowers and thrives with roses that are equally hardy. A good pairing is deep purple C. v. 'Polish Spirit' with pale pink 'New Dawn' rose.
Early bloomers. Consider C. alpina, a tough, sun-loving climber with small, nodding single flowers. Pair hardy and fragrant, yellow-gold 'Autumn Sunset' climbing rose with deep blue C. a. 'Francis Rivis' or the dark purple C. a. 'Helsingborg', recipient of a 1993 Royal Horticultural Society Award of Garden Merit.
Midseason bloomers. With its pale lilac bell-like flowers, C. viticella 'Betty Corning' is a popular choice for prolific blooms from June through early fall, and it is an outstanding companion to the summer-flowering red 'Blaze' rose or the lacquer red, repeat-blooming 'Altissimo' rose.
For a larger-flowered midseason clematis, pair hybrid 'Ville de Lyon' (red flowers and golden stamens) with the peach-yellow, repeat-flowering English rose 'Graham Thomas'. 'Ville de Lyon' is both hardy to zone 3 and heat tolerant to zone 10. For a traditional look, match white C. henryi with crimson 'Madame Isaac Pereire', a repeat-flowering bourbon rose.
For mid- to late-season blooms, consider small-flowered clematis such as C. orientalis and C. tangutica. Both have beautiful seed heads that last long after the blooms have faded. The vigorous C. o. 'Sherriffii' has yellow lantern-like flowers and silvery seed heads, while C. t. 'Bill MacKenzie' boasts nodding deep yellow flowers good matches for rugged orange, pink, or white roses, such as the white, repeat-flowering 'Climbing Iceberg'.
Late-season bloomers. With its rich purple blooms, C. viticella 'Etoile Violette' is a favorite among many gardeners, especially in combination with the repeat-flowering climbers 'Pink Perpetue' or yellow 'Golden Showers'. 'Etoile Violette' also makes a striking combination with the hardy 'Henry Kelsey' rose, which produces repeat flowerings of red blooms with yellow stamens. Small-flowered hybrid C. texensis 'Etoile Rose' has deep pink, nodding bell-shaped blooms that go well with the fragrant red 'Dublin Bay' rose, a repeat-flowering climber that has a tendency to remain a shrub.
Continuous bloomers. 'Perle d' Azur' is a popular large-flowered hybrid clematis that blooms continuously from June to October and is cold-hardy to zone 3. Its semi-nodding sky blue flowers are a beautiful match for the popular apricot-pink rose 'Compassion', which can be used as a short climber or shrub. Pink 'Comtesse de Bouchard', a large-flowered hybrid clematis, is a favorite cold-hardy choice that also adapts to zone 10. It is nicely matched with the climbing floribunda rose 'Handel', which has creamy white petals with rosy pink edges.
Clematis for shrub and ground cover roses. The small-flowered hybrid 'Mrs. Robert Brydon' (C. jouiniana) is a popular, fragrant clematis. It is vigorous and nonclinging, with hyacinth-like lavender flowers. This late bloomer is an easy, beautiful, and reliable companion for the small, peach-apricot floribunda rose 'Sweet Dream' or the English shrub rose 'Abraham Darby', which produces large, fragrant blooms in peach-pink and yellow.
'Huldine', another large-flowered hybrid clematis, has pearl white flowers with mauve hints on its sepals' undersides. This late but long-flowering clematis is vigorous and free-flowing. Because it grows well horizontally, it is a great match for 'Flower Carpet', a repeat-flowering ground cover rose with deep pink, white-centered flowers.
Lastly, C. viticella 'Venosa Violacea', a late-flowering hybrid, produces large purple flowers with white veining. It makes a wonderful match with the salmon-pink shrub rose 'Bonica'. Both plants are ideal for use as ground covers.
The ideal location for both clematis and roses is in full sun away from wind. Wind can damage clematis by tearing the leaf stems from their supports. Heavy winds can also damage climbing roses because they do not have a clinging habit. If possible, place the clematis where its root system will remain shaded and the soil will hold moisture longer, as on the shady side of a shrub rose. From there, the clematis will grow up so it can bask in full sun. Both plants need a lot of water, but clematis are more likely to suffer from lack of it. Provide each new plant with at least 1 gallon of water per week, more in hot weather.
Ideally, plant roses and clematis in spring. The planting hole for each should be large enough to accommodate its root system -- about 1-1/2 feet in diameter and 2 feet deep -- with dimensions varying depending on whether it has been purchased bare-root or in a container. Both plants love rich, moist, well-drained soil, so amend the soil before planting with compost or well-rotted manure and a handful of superphosphate.
Plant roses with the graft union 2 to 3 inches below the soil line in cold-winter climates, slightly above the soil level in warmer regions. Plant clematis with the crown 2 to 4 inches below ground level. Before planting container-grown clematis, gently loosen the thick roots of the large-flowered hybrids, but be careful with the fibrous roots of the small-flowered plants. Simply spread the roots of bare-root plants before planting.
To minimize water and nutrient competition and to make pruning easier, plant clematis at least a foot and preferably 3 feet away from the host rose, and train the stems into the rose with canes, stakes, wire, or string. If you plant the companions near a wall, place them at least 1-1/2 feet from the wall and guide their stems toward the wall with a stake.
Mulch new plantings to help retain moisture, suppress weeds, and add nutrients to the soil. Apply mulch after the soil has warmed, covering a circle 1 foot in diameter around the plant to a depth of 2 to 3 inches. Keep the mulch 4 inches from the stems to reduce the chances of wilt developing. Fertilize in early spring before flower buds start to swell, and again in fall; use organic compost or composted manure, as well as liquid fertilizer in the spring. Discontinue liquid fertilizer when the plants are in bloom because it will shorten their flowering period.
Prune established roses just as growth begins, usually in early spring. Train the long canes of climbing roses as horizontally as possible, removing old and dead wood. Prune young shrub roses to about 6 to 8 inches from the ground.
When it comes to pruning, clematis fall into three categories. Early-flowering kinds don't require pruning; just clean them up after blooming. Lightly prune midseason bloomers in late winter or early spring. Prune late-flowering plants in late winter or early spring, back to just above the lowest pair of strong buds. If late bloomers look messy in fall, remove dead growth, particularly off a climbing rose partner, and prune to 2 to 3 feet above the ground, leaving remaining stems to protect the crown of the plant through winter.
Take care to regularly deadhead both roses and clematis (except clematis that display ornamental seed heads after flowering), especially in the first two years.
The most common diseases to affect roses are black spot, powdery mildew, and rust, but many disease-resistant roses are available. Clematis are primarily affected by wilt or stem rot. To control this, cut the plant stem below the infected point and destroy it. Disinfect your shears between cuts. Most plants will resprout even if cut to the ground, although they may appear dormant for a year or more. Take heart: once a clematis has developed woody brown stems, it is far less likely to be affected by wilt.
Beth Marie Renaud is former managing editor at National Gardening.