As long as their daylight is 18+ hours, they will remain in veg which leaves out autos. But the light would have to be of sufficient intensity so that flowering is not triggered. I had my current GDP by the window sill thinking the street lights and other external building lights would not trigger the flowering period but by the time I had space in my tent, she had flowered enough to develop heavy pistils then re-vegged then flowered again. As a result, GDP gone wild and stretched right out.
2 Likes