:smoking: Hey mates! I think one of our founders, Muddy, wrote a nice piece on flushing vs. cleansing, in the New Growers forum, as a sticky article,... Definition-wise, folks tend to interchange them, even the industry refers to a "flush" period, so small wonder about term confusion! Big picture, it's about making sure the plant has little stored reserves left in it by harvest time. Nutes like N and P, (others too) are taken in whether the plant needs them or not, it's automatic; excess get stored, usually in the fans, roots,... excess N and P especially can foul the smoke if there are lots of reserves still stored by harvest, this is solid fact!,... a good sign that things are clearing out well is your fan leaves getting tapped out-
A plant that looks a bit haggard in the leaves by harvest is something of a plus!
Basically,
cleansing refers to a period of time prior to harvest when nothing but water is given, usually about a week... This period depends on how heavily, and what, you've feed.... With organics, no need to at all! Moderate feedings, with regular plain waterings, and some run-off, maybe just a few days,...
Flushing I define as actual heavy pour-though waterings of the medium, typically around 3x the pot volume; this is intended to remove accumulated salts, excess nutes, sometimes to help with badly off-pH,... Heavy/aggressive feeding, use of powerful PK boosters, cases of too much N into bloom... some folks do an actual flush to remove excess, and force the plant to use up internal stores more... In any case, it's about
purging the medium, not the plant itself directly! There is no "washing out" or 'rinsing" of the plants internals stores like it was a soapy cloth, nute ions just don't move like that in reverse.. the plant does NOT export such ions from the roots... Flushing takes away the excess in the medium so the plant is forced to tap into internal sources, and use up potential excess stores,...
there's plenty of arm-flapping controversy about all this, but I'm just painting some broad strokes here! Some question flushing/cleansing at all,... but a hint at truth-- look at many of the feed schedules out there, and they will have a "flush" (cleanse) period that has little to no nutes/supplements used for typically about a week,... If it was all BS, the manufacturers would gladly have you use (synthetic) nutes up to harvest so you use up more product--- $$$...!
I agree, flushing just prior to actual harvest is not a wise thing to do, if for no other reason than the excess water uptake it causes... a flush should be done several days at least before harvest, so those extra stored nutes are consumed,.. watch the fans leaves, they are telling you a story!
The other side of the coin here is about over-starving the plant, too long, too much, and causing sufficient stress that quality declines,... there's truth here too,.. translocating nutrients, those than even can be (this is what mobile/immobile nutrients mean, whether the plant can remove them from established tissues to new growth where it's really needed) is energy intensive, energy not going into buds/terp's/cannabinoids production.... Finding that happy middle ground for the plants, timing it for optimal ripeness as you like, and getting nice "clean" buds with booming terp's, is part of the growing skills forte that only experience can really provide,...
