Iowa State University Extension and Outreach offers a practical guide to one of the garden’s most versatile flowering vines








Clematis, often called the “queen of vines,” is a reliable choice for trellises, fences and perennial borders across the Midwest. With more than 250 species and hundreds of cultivars, gardeners can select types that bloom from May until frost in a wide range of forms and colors.

“I always tell gardeners not to worry too much about the pronunciation,” said Aaron Steil, consumer horticulture extension specialist at Iowa State University. “Whether you say, kla-MAT-us or KLEM-a-tis, these plants  are some of the most beautiful and diverse climbing vines and perennials and have earned their place in the landscape.”

Types


Most gardeners are familiar with vining clematis, which climb by twisting their leaf stalks around supports and may grow 8 to 12 feet or more in a season. They require a sturdy support such as a trellis, fence or deck railing. Shrub or bush types also exist. These grow upright like herbaceous perennials and typically die back to the ground each winter. Some bush varieties stand well on their own, and others have a rambling growth habit that benefits from support from a stake, cage, or nearby plant.


Flowers range from small bell-shaped blooms to large star-shaped forms in pinks, purples, blues, lavenders and whites. Some flowers have contrasting stripes or shading, and a few are fragrant. After flowering, many produce attractive silvery, feathery seed heads that add multi-season interest.


Clematis are grouped by bloom time. Spring flowering types bloom in mid spring on growth produced the previous season. Repeat bloomers flower in late spring to early summer on last year’s stems and then produce a second flush of flowers on current season growth in late summer. Summer and fall bloomers flower on current season growth from early summer into fall.


“By choosing clematis from different bloom groups, gardeners can have flowers for much of the growing season,” Steil said. “In colder climates like Iowa, varieties that bloom on new growth, including the repeat and fall bloomers, tend to be more reliable because they are less impacted by winter injury.”

Planting clematis

Proper planting is key to long-term success. Clematis perform best in well-drained soils with ample organic matter and access to sunlight. They prefer full sun with at least six hours of direct sunlight each day. They tolerate light shade, but flowering is often reduced.

Plant clematis slightly deeper than it grew in the container, burying the crown or first set of leaf nodes below the soil surface.

“Planting a little deeper than the original soil line helps protect the crown, encourages additional shoots and improves plant resilience, resulting in a fuller plant over time,” Steil said.

Gardeners should also be patient. Clematis often have limited above-ground growth during the first year or two after planting while they develop extensive root systems. Once established, they grow vigorously and produce more abundant blooms.

Steil added, “After planting clematis, it is often said that the first year they sleep, the second year they creep and the third year they leap!”

Care and maintenance

Water regularly during dry periods, especially in the first growing season. Once established, clematis benefit from consistent moisture and good drainage.

Apply mulch annually to conserve soil moisture and moderate soil temperatures. Clematis grow best when the root zone is kept cool.

“You will often hear that clematis like their head in the sun and their roots in the shade,” Steil said. “Mulch or nearby low-growing plants can help create those conditions.”

Fertilization needs are modest. An all-purpose fertilizer applied once per year is typically sufficient for most home garden soils.

Pruning clematis

Pruning is often the most confusing part of growing clematis, but understanding bloom groups makes it easier. Proper pruning helps improve flowering and maintain plant size and shape.

Spring bloomers require minimal pruning. Remove dead wood at bud break and prune lightly after flowering if needed.

Summer and fall bloomers should be cut back to 6 to 12 inches in late winter or early spring. This encourages vigorous new growth and abundant flowering later in the season.

Repeat bloomers are more flexible. Prune out dead wood in early spring to preserve both spring and summer blooms. If pruned more heavily, they will still flower later in the season, but spring blooms will be reduced or lost.

“The key is knowing when your clematis blooms,” Steil said. “If you prune at the wrong time, you can remove the flower buds and end up with a plant that does not bloom that year.”

Common problems

Clematis are generally reliable but can encounter a few issues. Clematis wilt is the most common disease and causes the sudden collapse of stems. Affected vines should be cut back to ground level, removed and destroyed. The disease rarely kills the entire plant, and new shoots often emerge, although flowers may be lost for that season.

Another common concern is a lack of blooms. This can be caused by insufficient light, poor fertility or plants that are not yet fully established. However, improper pruning or winter injury are the most frequent causes.

“If a clematis is not blooming, the first thing to check is how and when it was pruned,” Steil said. “In many cases, the buds were removed or killed by winter before they had a chance to flower.”

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