Hi there. I need to make giant jar cake. It will take quite a few layers of cake to make it big enough. Do i need to put cake plates/boards between the layers? I don't want there to be a ridge in the fondant where the board is...if it's exactly the same size of the cake will it be fine? It's probably gonna end up as 7 or 8 layers of cake at least!
You should dowel every four to six inches of cake.
...oh, and your boards should be cut slightly smaller than the cakes so they will not show under your fondant. HTH.
And you need support straws between each layer plus the plates. But because your cake is so tall you might want to consider using rounds of foam core boards.