Signs of Sunlight or Water overexposure in Plants
Answer by Alessandra Martellacci:
If you are talking about succulents, then they will actually get a sunburn that looks like a sunburn (ask my aloe vera) if they get too much sun and rot from the inside if you over water. More water will not help the sun burn. Only moving the plant to the correct lighting will solve that.
For leafy plants, it can be more complicated as over watering and too much sun often look the same; wilting, browning or yellowing leaves, dropping leaves, blossom end rot… Check the specific water and sun requirements carefully for each and every plant. More water can be given to plants on very hot, sunny days (members of the nightshade family and leafy herbs are big for this), but if they aren’t in the right spot, then you will be permanently fighting an uphill battle and it would be prudent to move the plant. Stressed plants don’t grow well and no amount of liquid adjustment will fix it.
Conifers vary widely, but usually brittle needles that break off easily are a sign of too much sun… or over watering.