Posted: 13/08/2015 at 01:11
Certainly, artificial light will have an impact on some indoor plants (such as christmas cactus and poinsettia) which are called "short day plants". These need a maximum continuous period of darkness (approx. 14 hours) to induce flower bud formation. Even a brief flash of light will prevent this as it causes a chemical in the plant (called phytochrome) to change its molecular shape which then inhibits the chemical processes to form the buds. However, it is the red and infra-red ends of the spectrum which are involved (not UV). Growers for the Christmas market use computerised systems in their greenhouses to ensure that such short day plants only receive the light which they need.
I would doubt that the intensity of street lights would have much effect on the doorstep chrysanthemums however! Hope that helps.