When is silver the hedgehogs birthday?

Answer 1

All we know is that Silver was born in the distant future of Sonic's world, and that he's 14. Since we're never given a date for any event in the Sonic timeline whatsoever, and since we don't know just how distant Silver's time period is from Sonic's, determining his date of birth is impossible.

If you are referring to the date when Silver made his debut in a video game, that would be the launch date of Sonic the Hedgehog. The earliest date is the North American release of the 360 version, which is November 14, 2006.

Answer 2

Silver the hedgehog's birthday is somewhere in June!!! =)