Nasturtiums (genus Tropaeolum) are celebrated for their vibrant, edible flowers and unique lily-pad-like foliage. While some types form compact, bushy mounds, others are trailing or vining, producing long stems capable of scrambling up a support structure. Achieving vertical growth requires selecting one of these longer, rambling cultivars, which adds color to a vertical space.
Understanding Growth Habits
Nasturtiums are primarily categorized into two growth habits: mounding and trailing. Mounding varieties maintain a neat, compact structure and are unsuitable for climbing. Examples include the ‘Alaska’ series, which features variegated leaves, and the ‘Jewel’ series. These cultivars are best suited for containers, edging garden beds, or use as a low ground cover.
Trailing or vining nasturtiums, such as the ‘Gleam’ series or Tropaeolum peregrinum (Canary Creeper), produce long stems that can be encouraged to grow upward along a support. Without a vertical structure, these plants sprawl across the ground, creating a dense, tangled mat of foliage. Selecting seeds or plants labeled as “trailing” or “vining” is necessary for vertical growth.
How Vining Varieties Scramble
Nasturtiums do not possess the specialized structures of true climbing plants, such as the adhesive pads of ivy or the coiling tendrils of peas and grapes. Their mechanism for vertical movement is scrambling or sprawling, relying on the long, flexible stems attached to their leaves, known as petioles.
These petioles allow them to wrap around thin objects they encounter. When a vining nasturtium stem contacts a narrow support, the petiole of a nearby leaf will curl and tighten its grip, anchoring the plant to the structure. This action pulls the main stem loosely upward, requiring a delicate, thin support to be effective. The plant uses its leaves as temporary grappling hooks rather than permanent anchors.
Choosing and Installing Support
Because nasturtiums utilize their thin leaf petioles for temporary purchase, the support structure must accommodate this unique growth habit. Thick wooden trellises or large-diameter poles are too wide for the petioles to wrap around securely. A more effective approach involves using materials with a small diameter, allowing the petioles to coil tightly.
Ideal supports include thin wire netting, small-mesh chicken wire, or lengths of simple twine strung vertically. Chain-link fences are effective, as the individual links provide numerous small points for the petioles to grasp. When installing, place the support close to the base of the plant, and gently guide the initial stems onto the structure.
You may need to manually wrap the first few stems around the support to initiate the upward growth. For gardeners seeking a less formal look, vining nasturtiums can be planted at the base of other sturdy, upright plants, like corn or sunflowers, allowing them to use the strong stalks as natural trellises. This trailing habit also makes them excellent candidates for planting in hanging baskets, where the stems can cascade over the sides, or for spilling over retaining walls.