As Regards Passion Flowers
What causes the leaves on passion flowers to turn yellow and drop off, and what can be done to keep them green?
Certified GKH Gardening Expert
A number of things can cuses this in plants, usually as a result of stress. This article will provide some reasons for yellowing leaves: https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm