it would be more of an issue as to how they were stored .. IMHO ...

were they toasted all summer in an very hot garage??? .. frozen all winter in a cold zone [don't know where you are???] .. properly stored seed can last a very long time ... but most of us do not store them properly ...

regardless.. what more can you do than simply plant them and find out???

ken

They have been in a cool basement in their original package, so near optimum I would say. As for planting, I need to get some seed starter mix first.
I am wondering if anyone else has been able to get annual phlox to sprout after a couple years?

They'll do fine. Seed Savers' Exchange regrows many of their seeds only every ten years, and they still have adequate germination to prevent their collections from becoming at risk for extinction. 3-5 years under decent storage conditions should provide decent germination rates. Go for it.

Martha