In hydro, I'm thinking a 500ppm 1:3:2 NPK ratio would be good for "flushing"
I remember hearing somewhere that you should have a 1:2 P to K ratio during the veg/stretch, 1:1 after stretch, and 2:1 for ripening, but I've never tried it myself, and forget the source.
I have a theory that low potassium toward ripening will allow the product to dry out faster and more evenly. This is not something I've tried yet so I could be full of shit.
I've also heard that low calcium will induce early senescence in flowers, while high calcium will prolong flower life. That's something I've wanted to experiment with.
Another theory is that high P levels inhibit starch synthesis from basic sugars, which is supposed to improve flavor and burn ability and smoothness on the premise that starch tastes like smoking bread.. Also untested, but on my list of things to try.
I really doubt the best approach is to just starve the plant of all nutrients.