Probably not wire as it tends to cut into the plant, and does not allow any movement in the wind. A soft jute type twine, twisted around itself a couple of times after the eye, making a kind of little stem - not sure how clear that is, from the eye, then gently around the stem leaving room for flexing and growth. For larger tougher plants that need tying in, the wire that is covered with a quite thick layer of foamy rubber is good, it use that for my big fig tree that I am training along a wall and fence. You just twist the ends around itself and it holds very well - but too bulky for your decorative things in the pergola.