Last year scientists sprouted a seed that was 2000 years old. Just goes to show, if stored properly, seeds can last indefinitely.

Can you post photos of your seedlings?

Yeah, never throw away seeds. My 7 or 8 yr old collard seeds (rescued from my employer's trash can) still come up - maybe not all of them, but enough. I also keep them in Tupperware in the frig.

Seed viability lists give brassicas about a 7 year sprout life. Think of all the varieties of Asian brassicas and you have a pretty good deal. Now if only the lettuce seed packets would germinate in year 2- typically lots of duds.

I am using decade old chinese veg seeds. Most still germinated, less than normal but still pretty good rate. Sadly many perished today as it was unusually hot in the sun room, before i could open the door.