Purloined Plant Prevention
I've had iris picked out of my front yard, and had solar lights stolen out of the front yard (back when they were new on the scene and expensive), but never had actual plants stolen. I'm cognoscente of it though. My front yard baskets are wired securely to the brackets. They can still be stolen, but it would make it difficult to get them off the brackets.
My alternative would be to plant poison ivy in my front yard baskets. They still might get stolen, but it would give me a certain measure of satisfaction.
Ever have something stolen from your garden?