Hello. Around 3-4 years ago I planted a line of red tipped photinias, approximately 3 feet away from each-other. The goal was to have a natural hedge border out front made of red tipped photinias. After all these years they look like this. I know there are many variables that constitute a healthy plant, but all-in-all I'm told we have rich soil, but I still used top soil blend when planting them, I use all-purpose fertilizer, and I use drip lines twice a week (30mins each cylce). I'm sick a lot with migraines so sometimes the weeds get a bit out of control like in this photo, but its rare. When I prune the tops, they look like they want to kill over the next day or so. My guesses are water schedule, when I prune, and/or the stuff I'm finding on the bottoms of the leaves (the ones that look unhealthy).
Anybody got some suggestions for maintaining this struggling potential?