Last spring, I planted two of these holly plants in the beds in front of our house. They were very healthy looking until this week. On both plants the leaves have turned a very light green and can be easily pulled off - they are not dropping off. I live in Massachusetts and we have recently had a lot of rain - three major storms with heavy rainfall over the last month. I have looked at several websites to try and find out what the problem is. Several sites have mentioned that there is a problem with overwatering. Will these plants die and have to be replaced, or should the leaves eventually go back to the dark green leaves that they had before?
Over watering causes iron chlorosis. This article will help you fix the problem:
https://www.gardeningknowhow.com/ornamental/shrubs/holly/holly-yellow-leaves.htm