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.
Along with zonal geraniums, there are 3 more types of Pelargonium: 1  Ivy-Leaf Geranium (Pelargonium peltatum) â As their name implies, these geraniums have a trailing habit and ivy-shaped leaves. 2  The flowers are smaller and less showy than zonal geraniums and the plants are often used as spillers in containers.