Petiole climbers are a very specialised growth type, and are most common in the Clematis. They wind their leaf stalks or petioles around thin objects and hence stabilise the plants in their upward growth. It is good to know that petiole climbers don't cause building damages....
A much better known group of climbers, which is described separately, includes the stem tendril climbers.
Apart from a few exceptions (Clematis vitalba and Clematis montana), petiole climbers don't develop strong and vigorous stem frameworks. Hence they require rather light and delicate support systems with rather small grid widths. Wire ropes are optimal, but thin rods as used in bamboo espaliers are very suitable as well. Thicker staffs such as in wooden espaliers require the use of plant ties.
Narrow-meshed grid structures such as trellis nettings (made of synthetic materials such as plastic or nylon) or chicken wire are suitable, though their disadvantage is that every year many lignified tendrils remain on the climbing support and may need to be removed painstakingly.
Wire rope systems with mesh sizes of approx. 25 – 30 cm such as wire rope systems 5040 or 5050 are most suitable. The vertical ropes may be predominant, which means that the meshes formupright rectangles rather than squares. Usually medium wire rope systems or even simple and light systems suffice.
Single vertical wire ropes are not very suitable, as they don't give the plant enough grip. Likewise, arrangements with only one horizontal wire at the top, where the flowers are to develop, are not very suitable. And systems with predominantly horizontal wires are also of limited suitability. Furthermore, mesh sizes which are too wide belong in this category, because it becomes impossible to achieve an entire covering of the area. However, should one tolerate or even wish to have a different growth form from the usual one, for example overhanging growth, then all these trellises may very well be suitable.
Systems with very small mesh sizes or tightly arranged wires are not optimal either, as they are not only expensive but they don't offer the plant any additional advantages.
Trellis systems which don't harmonise with the expected growth habit of the specific plant are totally unsuitable.