Q.Borwn Leaves on Old and New Plants
I planted ten new Azalea plants this spring following the planting instructions on the company’s website. The edges of the leaves are turning brown on some, but not the others. I assumed I had done something incorrectly – too much fertilizer, over/under watering, etc. Today, I noticed the edges of my Holly bush leaves were also turning brown. These are mature bushes – about 15 years old and in a separate part of the backyard. ANY advice would be greatly appreciated!!

Certified GKH Gardening Expert
This could be a number of things--too little or too much water, over fertilizing, leaf scorch (if planted in too much sun), etc. It may help to prune the plants to help rejuvenate it. This article has more information: https://www.gardeningknowhow.com/plant-problems/environmental/what-causes-brown-edges-on-leaves-of-plant.htm