There are a number of potential responses to this question, depending on who you ask and the context you’re in. Plants generally don’t like a lot of light, whether it’s blue light or not.
Every living creature, including plants, requires a period of rest when there is no light. It’s time to rest and repair. Because of this, it is generally advised to offer your plants at least a few hours of darkness per day.
Another situation where too much blue light could be harmful is if it makes less red light. For instance, plants that are primarily exposed to blue light have a tendency to be shorter and have blooms and bulbs that are smaller and less strong. They become taller and produce more fruit and blossoms when exposed to red light. Red light can also aid in strengthening and completing the root system.
So, certainly, too much blue light can be problematic if there is no rest or if it displaces red light.
