Get yourself a magnifying glass and look at the trich's (crystals on the buds) They should be milky/clear in color. You want to wait until the crystals are about 60% Amber 40% Milky, then chop her down and let her hang dry. Your plant isn't going to produce any more buds, or grow and fatter, or anything. The last thing that it's going to do before it dies is mature the buds that it has already put on. This is a good thing, because it means that your going to have something to smoke, just not as much as you could have had. If I were you I would invest in a jewelers loop, or some kind of magnifying glass, and keep an eye on those trich's , once they get about 50%/50% milky to amber I would start to flush with Clearex, or what ever salt leaching mix you want to use. Let it sit for a couple of days. Since your roots are so far gone it's going to take the plant a little longer to uptake the clearex, so be patient with it. Once you feel satisfied that there is no more bad tasting nutrients in your buds, chop them down, and get ready for the cure, and the really smelly part...
, <3,
, And Good Luck Homie!
~VLO