Propagation by Cuttings in Humidity Chamber (Sandpaper Vine)

I've seen the Sandpaper Vine's flowers many times in photos all over the internet and found them amazingly beautiful. The fact that the flower colors of violet and blue aren't as common as the reds and yellows in the tropics makes this vine even more appealing to me.

The Sandpaper vine's scientific name is Petrea volubilis. Unlike the white Porana volubilis (which I have in a container trellis), this vine isn't aggressively twining at all. Petrea volubilis's other common names are Queen's Wreath, Purple Wreath, Blue Bird Vine and Fleur de Dieu (Flower of God)).