self germinating seeds ?

Self-germinating? Never heard of that  no seed can be guaranteed to germinate - so don't understand what you've been told.

There's: self pollinating, self-fertile, self seeding.

Probably the latter was meant, as parsnip, as an umbellifer,  commonly self-seeds.  This might have even happened to some plants in this warm spring spell, we got earlier in the year. And it is said, that you need very fresh seed for parsnip to germinate. This could perhaps be, what he was on about.

Self-germinating there just isn't. Maybe, this word could be applied to seeds that germinate inside their fruit, like tomato seed sometimes does.