The absorbed energy is converted to heat energy. The scenario you mention with the LED is very close to the blackbody problem known as the ultraviolet catastrophe.. There is a Wikipedia article about it here. What happens in the situation you described is that the light proof box gets hotter.
Diagnosing rust on geraniums can be a challenge for growers. Rust begins with yellow spots on the underside of the leaves and can rapidly progress with brown fungal spores called pustules in the center of each spot. The pustules are raised up off the leaf surface and feel rough to the touch.
Anything under 26 degrees will kill the plants. Ideal temperatures for growing geraniums are 70 to 80 degrees during the day and 60 to 65 degrees at night. See source for more information on growing geraniums.Source(s): http://www.backyardgarden.info/geraniums...deal temperatures for growing geraniums are 70 to 80 degrees during the day and 60 to 65 degrees at night. See source for more information on growing geraniums. Source(s): http://www.backyardgarden.info/geraniums...