Question=What level do I
need to be to go to Grizzleheim?
Hi, Blake. Good Question. I'm going to wikia for the answer on this one.
Baldur Goldpaws in Olde Town gives you the prequest to go to Grizzleheim, and this part of the equation you can complete at any level. After that quest, Baldur gives you the trade voyage quest where you can enter an instanced version of Northguard. So, in a way they give you a really cool pre-look at Grizzleheim early on in the game.
However, it ends there until you hit 20th level. At 20th level you go to Merle Ambrose and he gives you the Grizzleheim quest.
. . . at least that's what wikia is telling me.
**UPDATE: I just checked with Bailey, who is level 18, and got this message**
So consider it verified!