Does my flowering room have to be totally light proof?

I'm starting to transition my plants into their flowering stages, but because of these cold winter nights I have decided to keep my grow room lit from 6 PM-6AM to avoid grow room temperatures of 60 degrees F and below. So during my grow room's lights out time, it will be daytime outside. I have an inline fan to exhaust outside air and I use passive intake by keeping a window open. I have covered the window with a layer of black mesh which blocks a good amount of outside light, BUT not all of it. It's still pretty dark in the room with the mesh screening, but would the remaining light that finds its way in be enough to adversely affect the flowering process? Any input would be great, thanks!

light leaks can cause loose nugs & hermi's

And slow flowering time alot.

And allow entryways for bugs/pests.

So any suggestions as to how I can deal with the situation?

Duct Tape. Or mylar and staple gun.

they sell black carbon air filters for furnaces at Home Depot and such. I have found useful and nearly light proof when covering passive 6" intake holes to outside.

rojotierra said:

they sell black carbon air filters for furnaces at Home Depot and such. I have found useful and nearly light proof when covering passive 6" intake holes to outside.

Click to expand...

Do you know if they sell them big enough to cover a regular sized window?

the one i bought was 24 inch x 24 inch. If window is open a few inches-one should work. Two for sure. Not expensive. They are easily cuttable to customize for your need. If there is a 2 inch opening in window-cut into 3 inch strips and gorilla tape together.

Good stuff, thanks alot man!