flushing is when your plants are burnt
otherwise, just slow down on nutrients towards the end, not to get "excess" nutes out of the soil but to just save money
on harvest day, don't chop during the light cycle, give the plants 12-36 hours of darkness then chop. I usually just wait until right before the lights turn on, then cut them down
what the plant does each night is stores away enough carbs to do its night stuff, and then when the lights come on the starches go back up into the plant and is what will give you that "chemmy" taste
to avoid extra starch just chop before lights on or whatever
seriously people thought i grew organic , and i say no i don't...
then they say well you must leech/flush very well, and i still say no
what i do, is never over-feed, and make my plants happy and green. I follow a 9-3-6 or 3-1-2 NPK ratio the whole grow and gradually increase feedings. Once a month I leech to get excess salts off the roots and allow them to uptake more. Leeching is just 3x medium size worth of water run through (example 5 gal gets 15 gallons)
at the end, flushing would be the worst thing, cause you want your plant to reach peak maturity or ripeness when you chop it, and how could you do that if it doesn't have any nutrient to feed from?
another question that made me quit flushing, do fruit growers or vegetable growers flush their crops? Fuck no!