I want to make a cake that has some fondant flowers on the side of the cake. The cake needs to travel in the car for about 2 hours, and I'm wondering if the flowers will stick well to a buttercream frosted cake, or do I need to cover the cake in fondant for the flowers to stick well?
Depends on the flower. If they are not big, thick and heavy there should be no problem.
Pipe a royal icing spike on the back of the flower OR make it in fondant so you can stick it actually into the cake.
Alwasy pipe a open circle of b'cream on the b ack of any flower you are placing. It will work like a suction to help hold it in place. Use tip 3 or 4 for most flowers.