How to Grow and Care for Clematis
Introduction to Clematis
Clematis are known as "the queen of the climbers" for good reason — these popular plants produce some of the most spectacular blooms in the home garden, with flowers reaching up to 10" across! Most clematis are woody, deciduous vines with blooms in a stunning array of jewel tones, including purple, pink, magenta, and yellow, as well as white and bicolor, many with a contrasting center of showy anthers.
About Clematis
The most popular clematis are long-lived, easy-care perennial vines that bloom in late spring or early summer, heralding the growing season with stunning star-shaped blooms followed by whimsical fluffy seed heads. Although the vines can be left to scramble through shrub branches or over a rock wall, they're at their most eye-catching when trained to a trellis, arch, arbor, or pergola. The blooms attract bees, butterflies, and hummingbirds, and the dense foliage provides a protected nesting spot for songbirds.
The Clematis genus includes hundreds of species, and plant breeders have introduced hundreds more hybrids. You'll find clematis in a range of heights and bloom times, as well as flower shapes and colors, so a bit of research will help you select the best variety for your needs and growing conditions.
Clematis vines can reach 15' high; however, there are compact varieties suitable for small gardens and patio planters. Most climb by wrapping their elongated leaf stalks (petioles) around a support. Because the leaf stalks are relatively short, the plants climb best on supports with narrow (1/2" or smaller) uprights or slats. They'll also readily climb up wire grids or nylon mesh.
Sweet autumn clematis (C. terniflora), a widely cultivated species native to China, blooms in late summer to fall. In some places this vigorous species has escaped cultivation and is considered an invasive species. Consult your local invasive species lists before planting it.
Pronunciation: Is it KLEM-uh-tiss or cleh-MA-tiss? Either pronunciation is fine.
Growing Zones for Clematis
Most clematis are hardy in USDA Hardiness Zones 4-9. A few varieties are hardy to zone 3, and some are more tolerant of heat and will grow in zone 10. If you're planting in containers, choose varieties that are hardy to two zones colder than your region; for example, if you live in zone 6, choose varieties hardy to zone 4. This is important because, during the winter, the soil in containers gets colder than garden soil.
Choosing a Site to Grow Clematis
Clematis prefer full sun (6+ hours per day), though they appreciate some mid-day sun in regions with hot summers. They grow best in rich, well-drained soil with a neutral pH that stays consistently moist. Conventional wisdom says that the plants like "their heads in the sun and their feet in the shade" so it's a good practice to plant low-growing perennials around the base of the plants to shade the soil, keeping it cool and conserving moisture.
Clematis are ideal for adorning entryways, brightening bland walls, adding vertical interest to perennial gardens, and shielding unsightly views. The dense foliage makes them a good choice for shading porches and patios. If growing in a container, choose one that's at least 18" in diameter with holes to allow excess water to drain.
Planting Instructions for Clematis
Clematis vines tend to be brittle and break easily, so handle young plants carefully. Loosen soil to a depth of at least 12" and amend it with compost to improve water retention. Adding some slow-release granular fertilizer will provide a steady supply of nutrients. Install a trellis or other support at planting time, taking care not to disturb the plant's roots. Apply an organic mulch, such as bark mulch or pine straw, taking care to keep it a few inches from the stems to minimize disease problems. Water plants weekly during their first growing season. Be patient; the plants will grow slowly at first as they establish their root systems. You can expect an attractive display in their second year, but they'll really bring the wow in subsequent years.
Fertilizer for Clematis
Clematis require plenty of nutrients to produce their abundant foliage and stunning floral display, so you'll need to apply fertilizer to keep plants healthy and vigorous. Apply a layer of compost to the soil at the base of the plant each spring, along with some granular fertilizer. If needed, you can apply a water-soluble fertilizer in mid-summer.
Clematis Pests and Problems
Clematis are relatively pest-free. Adult plants resist nibbling by deer and rabbits, though young plants should be protected from them. Provide plants with good air circulation to minimize foliar diseases, such as powdery mildew. Aphids and spider mites can be controlled with insecticidal soap. Some clematis are susceptible to a wilt disease which causes plants to collapse and die; unfortunately, there isn't a cure for this disease.
Ongoing Care for Clematis
Once the plants are established, in addition to watering, fertilizing, and replenishing mulch, clematis require proper pruning to maintain their vigorous growth and flowering. There's a bit of mystique around pruning clematis, with species and hybrids categorized in groups depending on their flowering habit and pruning needs. In a nutshell: Spring-blooming clematis produce flowers on the previous year's growth and should be pruned after they're finished flowering. Those that flower in early summer produce blooms on the current season's growth and should be pruned in late winter.
