I heard that if you put your plants on 14 hours on and 10 hours off the last 3 days of flowering before you harvest, it will increase you potency... Is this true???

I'm not 100% on potency, but it will increase your yield marginally.

Hell yeah I think I will do that then....

Eveybody would like to boost thier potency - I know I would! But the truth is, all the "tricks" are just that, tricks (they don't really work). The one "possible" exception is augmenting your flowering cycle with some extra UV-B light (like a reptile light). Never really tried it myself, but some respected growers have claimed "moderate" potency improvements. The added UV-B light makes logical sense, but the effectiveness is still a controversial issue!


But the good news is, you can flower with 14 on/10 off - not just the last three days, but most of the cycle! Start them at 12/12 for a few days, or a week. Then, each day, add an extra 10 minutes to thier light schedual - and take 10 minutes off of thier dark scedual. In less than two weeks you will be down to 10 hours of darkness/14 hours of light - wich will increase your yield substantially. The trick, here, is to "replace" that last, lost, 10 minutes with some far-red light spectrum - about 710nm. Cheap quartz-halogen lights are good for this purpose (they're not good for anything else in growing!).

The reason this works is because the "far-red" spectrum is the last source of light that the plant receives (as opposed to "full-spectrum" or arbitrary photons of varius wavelengths). Far-red light, at about 710nm, acts like "Knock-out Drops" on short day plants like cannabis; as long as it is the last spectrum they see before all the lights go out for the "night". In other words, the plant "goes to sleep" immediately, thus producing more "sleep hormones" in a shorter period of time. If the last light that the plant receives is in the near-red, or red spectrum (about 620-690nm) the plant takes longer to "drift-off" to sleep (requiring the normal 12 hours of darkness to produce the "sleep hormones" needed for flowering).
This is one of those "tricks" that will work, but it wont increase potency - it will increase bud production though!