recommended is 68 to 72% to maintain freshness; i have found red trichs won't form inless humid drops below too 65-68% the trichs still go red but it seems to take longer; ancient egyptian texts talk of 67% being optimal to bring out the "third eye of the cannabis plant" ........real interesting reads. anyways i use 67% for all these reasons, but i've also cured very long in jars and have to say that the trichs still turn red in the jars but the bud losses almost all it's smell(very faint smell that's very pungent) and alot of it's flavor, also the stoneyness and the soaring high of either kinds of strains is diminished completly and changes to a more.....mental high...where as the humidor maintains more flavor and smell upon breaking. the buds however after 24 months always smell like spices....almost like curry in a way