Sorry mate but my advice would be not to bother... if you really fancy doing a scientific experiment, use a different variable. Different nutes, different light, different wall covering (paint, mylar, foil) anything which is likely to have a positive effect, I'll bet my grow and my house that nothing beneficial will happen to your plants if kept in the dark for 2 weeks. The whole 2 weeks/1 week/ 48 hours darkness before harvesting was debated in detail on overgrow - I did not see one side-by-side experiment that made the blind bit of difference. The main positive contributers were just "wow look how crystally my plant is, i left it in dark for the week before that must be it!!!111"
Bluefunk Reviewed by Bluefunk on . turn the lights off altogether for the final 2 weeks? I got this on this site: http://www.white-widow-seeds.com/ Quote: "Flowering Time: On both mediums it is suggested to flower (12 hour light) the White Widow for 8 weeks, but 10 weeks will really give you the crystals you are after. We suggest the final 2 weeks of the flowering cycle to turn the lights off altogether - or at least down to 8 hours. This keeps the flowers from regrowth and stresses the plant into giving up its last drop of goodness as crystal to protect the flower...try it!" Rating: 5