Plants don't glow in the dark. Bioluminescence doesn't occur naturally in plants. Some plants, like tobacco and the orchid, have been genetically modified so that they can obtain bioluminescence.
Bioluminescence is incredibly taxing on metabolism. While one may be able to splice luminescence into a plant, the glowing plant will be miserable. Plants are not designed to bioluminesce; it would require an enormous amount of energy to maintain all basic plant functions and also bioluminesce. There are many patents for methods to force plants to bioluminesce. One particular patent did cause the plant to produce bioluminescent flowers, but it also introduced sterility. Most of these methods infuse plants’ genotypes with luciferase, but there have also been attempts to infuse plants with aequorin, the bioluminescent chemical found in some jellyfish. With advances in the knowledge of the chemistry and biology of bioluminescence, genetically-engineered bioluminescent plants and animals may become as common on Earth as on Pandora!
Through a very long process of natural selection, bioluminescent organisms have developed the ability to enhance light production through physiological, molecular, anatomical, and behavioral adaptations. This occurs because the bioluminescence imparts an important ecological advantage to the organism. It is the ecological context that provides the driving force for natural selection. In order for an organism to use bioluminescence that has been artificially induced there should be an ecological role for the light emission. To produce light for the wrong reason or at the wrong time would be a deadly mistake.