You will never stop them, tried various things over the years. They don't like the smell of orange as Nanabilly said, everytime I eat one I put the peel where I know one tries to get to. As for your planter, cover it until you have plants or put sticks in it (maybe add some string around them) or I too have put something prickly - pyracantha or holly from my plants - to keep them off.
My OH has now made wooden frames to put nets over for the veggie beds because everything he has tried hasn't worked. Bottles of water, cd's flapping about, scarers that look like cats etc.