I have a very healthy 7ft/2m Tabernaemontana (Sweet Love) next to a slightly smaller Photinia Glabra Rubens. The Photinia is now dying back where its branches start to intermingle with the Tabernaemontana. Could the Photinia be allergic to the Sweet Love? Is the Sweet Love toxic in any way? The Photinia has bright red new growth on the side not touching the other plant.
Certified GKH Gardening Expert
It should not be causing harm by simply touching. What is likely happening is the Tabernaemontana is blocking sunlight from reaching that side of the photina. Since there is not enough sun, the plant will be lax in growing on that side and will instead focus on the side that does get sun.