Fully oxidized tea leaves for a robust cup.
I've gotten a good feel for how long some teas last--a few months for sencha, for example, and several years for many Assams. What about Darjeelings, though? And is there a big difference between first flush, second flush, and autumn flush? Or is what really matters the individual tea and how it's processed?
Fresh teas have a quality all their own, but I have many Darjeelings that are 3 years old and still very good. They are kept in airtight canisters. None have gone flat. All were top quality when fresh. All were 1st and 2nd flush.