Growing Under Lights and Windowsill

[Linda3406]

I have all my orchids on a large picture window that faces southeast, but maybe more east. This particular window is shaded by some trees until about 8 am, then my eave hangs out pretty far, so by 11 the sun coming in is not so bright. SO, I use lights also. I have (4) 2 bulb lights hanging over plants. My question is, how long should I leave the lights on for adequate growing and flowering? The third pic is not really that dark, just can't seem to get this picture lighter.