Okay this may seem like a silly question but I am thinking of entering a cake decorating competition and wondered how long before the event I could make the cake and start decorating. The cake never has to be tasted or eaten by anyone so it doesn't have to be fresh or anything just to hold its shape and stay put (it does have to be cake tho, cant be dummies).

Thanks for relpies =)

You should be able to start it whenever you'd like.

The cake will start to grow mold in about two weeks, because the moisture is held in with the buttercream or fondant that is sealing it (but the mold won't be seen unless the cake is cut).

Shortening-based buttercream won't mold in an airtight container at room temperature for many months (usually more than 18 months) and it can't mold once it's air dried... it might start to crack or turn yellow but not for a long, long time.

from my experience entering a cake competition where you had to use real cake for the sculpted cakes division i found that the cake even once covered in buttercream dried out and shrank just a little bit. the only place that mold forms is where the cake touches the board or internal supports, but the icing either buttercream or fondant will be fine. If your entering a comp you usually have to also show step by step pictures, so remember to take some.