So called professionals

Yep, they still germinate but the percentage rate drops off quite a bit faster than other things like brassicas. It's a myth that parsnip seed is only good for 1 year, I've had good results from out of date packets. Spring onions I have noticed get a bit patchy after a few years. Carrot seed I got from Real Seeds years ago still germinated well after 4 years. How old the seed is before it's packaged is very important: a company like Real Seeds sell very fresh seed whereas we have no idea when the seed from T&M was harvested, only the year it was put into the packet.