Here is where things already go a bit sideways - I lose terps after mid flower. My plants stop smelling as nicely. I'm not talking about nose-blindness. Others notice it too. It's as if my terps are disappearing. My tent smells like berries, gas, fruity chewing gums, everything. And suddenly, these smells just disappear. As if something just grabbed all the terps.
This happened to around 16 plants now, stretched over a few grows, 4 of them being photoperiods from Square One, called Frozen Bag. I thought I'll switch it up for once, as all my autos lost their terps & I just thought it's an auto thing, but the same happened to my photos. Seriously, my plants sometimes look like cup winning images, but once you smell them, you'll be like "what the hell, there's nothing".
My drying conditions are rather stabilized, and I tried two methods this time - Low temps (10°C / 50F) with around 55-60% humidity, and the usual 60/60 drying method. One run also had a higher temp drying at around 70-75F / 20-24°C and 55% humidity for 2 days, and then 60% afterwards to let them dry out slowly a bit more. My drying times range from 7 to 14 days depending on bud size and density. I sometimes hang up single full stems with side branches, sometimes I just quarter the main stem up and hang the large pieces. Always dry trim, never wet trim. Low airflow, one big 12" fan blowing against the opposite wall on low setting, causing some air movement, but not enough to move the plants around, just enough to feel air moving on my skin if I stand there. I dry in an extra room I have no use for.
I trim them as usual as soon as they're dry, bag them up in grove bags, and they stabilize at around 61% humidity most of the time, and go to around 58-60% over the next few weeks. Everything works out just fine here. but the terps?
I end up with wood terps. All my plants end up smelling the exact same. Each and every genetic, strain - Wood, chocolate-ish wood. It has some resemblance to weed, but it's 99% cardboard and wood, as if everything died.
Hey Kaz! ...I know this WTF mystery all to well myself, and honestly, I can't finger any one thing for cause --> effect.... Auto's and photo's, inside and out...
Big picture, terp' production is dynamic, it may cycle up and down during flowering... There are several rabbit holes to go down on this, a whole damn lecture series really, so I'll throw some
broad strokes out there...
-- your grow MO seems fine to me, ditto for dry and cure... Not the cause that I can tell, and doing that right doesn't wave a magic wand to bring back what ain't there to begin with.
-- big thing missed here by some is the
fade out while live, sometimes early on....
-- for a fact, some pheno's will just be inferior for aroma production, it's the inherent gamble of all seeds; solid breeding, quality lines play big roles but nuthin' is "locked in" 100%...
An example from last season: two Lemon Drizzles, usually a solid cultivar, but I got one (the better looking and more resinous) that was nose blank as a piece of paper! The other had decent aroma, but not what it should have been...
-- nutrition and particularly, the right emphasis of which ones at the right time is another strong influencing factor. Certain micronutes are very important to terpene production; you can have all the PK right, but the terp' machine needs other parts than this! Micro's are critical catalysts/co-factors in secondary metabolite production, and it's possible to have that bottleneck things even if there are no overt deficiency symptoms...
Sulfur plays some role too, but isn't literally part of terpene components, but it is part of other aromatic compounds that give that classic skunk odor, "garlic/onion"....
Keep in mind there is so much synergistic action going on with all this, cultivar to cultivar, pheno to pheno, even plant to plant, it's really quite complicated

LOL
-- I have had plants very near harvest with fantastic aroma going on (at the time), and 36hrs later, morning of chop time, it goes quiet for no fucking apparent reason

....I've even delayed it because of this, but not always to good effect, and at the risk of going past prime ripeness...
What's most aggravating about this (for me) is that other plants are just fine for aroma! I grow is a sort of super soil with light amendments added in to butt-cover the things I mentioned (micro's, S, PK at the right time and amounts)...Si, kelp, humic-fulvics, inoculants...
*edit*-- spaced the follow-up

-- which is here you have plants getting pretty much all the same everything, so inputs are not bloody likely to be the core of the issue for such disparities...
Environmental factors are in play too, but nothing I see in your grow, or even mine, that could be the cause of shit aroma production,... heat, cold, wind,... But some of these (and pests too) can actually stress the plant and help magnify terpenes, so again, barring extremes, it's not the culprit to finger!
Daily wear and tear (outside mainly) does deplete terpenes which is why many I know harvest in the morning...
...gotta run, but mull over this and chat some more later....
