I asked the same question. Some good replies in here:

http://boards.cannabis.com/advanced-...e-harvest.html
Delta.9 Reviewed by Delta.9 on . boiling water! hey guys really interested to hear your views on this,a m8 just came round to check on my ladies and told me that a couple of hours before harvesting pour boiling water on the roots of the plant and all THC in the main stem will shoot into the buds. how true is this?:wtf: Rating: 5