What cause burn grades on my indoor plants, once on one plant, twice on another plant?
Answers: Too much fertilizer...if your fertiling with a dry slow time release and it get on the leaves..this will burn them..then if you are using a sea soluble spray type fertilizer..too much on the leaves will burn it as well..
You probably get some water onto the leaves while watering them. Then, if a plant stands close to the skylight, the sun can make these spots of dampen act close to a magnifying chalice and burn the leaves. That's also why you should only sea outdoor plants in the morning beforehand the sun is too high up or contained by the evening when it's low.