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 their pretty flowers, most have beautiful foliage. Most geranium plants will produce more flowers if planted in a sunny position. Geraniums will grow in partial shade, but flowering may be reduced. Geraniums prefer well drained soil and are not particular about soil type as long as it is well drained.Geraniums are not heavy users of fertilizer.Apply a light amount of 20-20-20 twice during the growing season.eraniums will grow in partial shade, but flowering may be reduced. Geraniums prefer well drained soil and are not particular about soil type as long as it is well drained. Geraniums are not heavy users of fertilizer. Apply a light amount of 20-20-20 twice during the growing season.