Most varieties of clematis are climbing vines that require a structure to ascend, such as a trellis, arbor, or fence. Without vertical support, they simply sprawl along the ground instead of creating the beautiful vertical display they are known for. Providing a sturdy climbing structure is fundamental for successful cultivation, though some varieties naturally grow as shrubs or groundcovers and do not require a trellis.
The Clematis Climbing Mechanism
Clematis vines climb exclusively using their leaf stalks, known as petioles. These petioles are sensitive to touch and quickly coil around any object they encounter. This unique mechanism dictates the type of support needed. Since the petioles are relatively short and delicate, they cannot wrap around thick structural elements. For successful climbing, the support material must be narrow, generally no thicker than a pencil or about 1/2 to 3/4 inch in diameter. If the support is too wide, the petiole cannot encircle it, and the vine will fail to attach.
Choosing Appropriate Support Structures
Selecting the correct support structure is paramount to a clematis’s growth and eventual bloom display. The structure must be sturdy enough to bear the full, mature weight of the plant. Supports should be installed when planting so the young vine has immediate access to its climbing surface.
Traditional trellises made of wood or metal are excellent choices, provided the individual slats or grid wires are sufficiently narrow. For wooden trellises, use thin strips or lattice with openings no more than six inches across. Wire systems, such as a grid of horizontal wires secured to a fence or wall, are often ideal because the wire meets the required thin diameter.
If growing clematis on a pole, pillar, or large arbor post—which are too thick for petioles to grasp—you must add an intermediary support. Thin materials like fishing line, strong twine, or narrow wire mesh can be wrapped around the thick structure. This creates a thin, climbable surface the petioles can easily coil around, allowing the vine to ascend.
Training the Vine to the Support
Clematis often requires human assistance, especially in early stages, to establish a successful climb. Young, flexible shoots must be gently guided toward the support structure as they grow. This guidance prevents new growth from tangling on the ground or forming a dense, unmanageable ball at the base of the plant. Soft materials like cloth strips, garden tape, or twine should be used to temporarily secure the main stems until the petioles take hold. Always use a loose figure-eight knot when tying stems to prevent the material from cutting into the stem as it thickens.
It is helpful to train the stems to spread out horizontally early on to encourage growth across the full width of the support. Without this lateral encouragement, the clematis will often shoot straight up, accumulating growth and flowers only at the top. Regularly checking for errant vines and loosely tying them in place throughout the season maintains a neat display.
Clematis Varieties That Do Not Require Support
While most popular clematis varieties are vigorous climbers, there are notable exceptions that do not require a trellis. These types are often referred to as herbaceous or shrub clematis, such as those in the Integrifolia group or Clematis recta. These types lack the strong climbing habit of vining cousins and grow more like perennials, forming mounds or sprawling masses.
Clematis integrifolia varieties produce multiple upright stems that may flop over when in full bloom if not given some staking. They are excellent for use as groundcover or allowed to scramble through the branches of nearby shrubs. Although they do not need a trellis to climb, they may benefit from a simple structure like a peony ring or stakes to keep them upright and tidy in mixed borders. These non-vining types offer the clematis flower without the commitment of a permanent vertical structure.