Watering at ground level in pots can still lead to harmful salt/mineral buildup.
When I am stumped, and not sure about stuff, here is, what I do. Treat with pyola both sides of leaves, good dose of 15 30 15 or 15 15 15 water soluable for quick results or use similar organic stuff like blood meal, bone meal. Add long term release granules such as osmote or other brand.
Switch to steady watering via ceramic gizmo and plastic soda bottle. Sometimes I also treat with fungicide. Cut off infected leaves. Pick the plant with the least fruit, and repot it giving a good inspection to the roots.
That’s all I can think of. I surely don’t know why they are doing well.
I will be looking for Pyola in the morning on my trip into town.
We started two summers ago with a bland colorless property with abandoned flower beds and nothing growing but Boxwoods surrounding everything in site, including around the base of oak trees and a redbud tree. Boxwoods are fine if thats what you like, but my wife likes color, and she has done well at restoring the outdoor beds.