Do you have that area you wish the kids would keep off? A wall you worry about them climbing on or falling off. Or are you that grumpy neighbor that hates kids cutting through their yard?
Try some of nature’s razor wire.
The ½” Barberry thorn I believe ends with a single cell. Man is it sharp; you just brush up against it and it sinks ¼” deep into your skin.
This shrub comes in five popular varieties. The Pygmy and Royal Barberry; they are burgundy leafed shrubs that stand 2 feet tall by three feet wide. In the standard sized Barberries you have the Rose Glow, Red Barberry, and the Yellow Barberry standing up to six feet tall by six feet wide. All sporting that “Hey Kid, Back off” look on their branches.
Truthfully thou I would deem Barberries as more of a barbed wire bush. If you want true razor wire go for the Pyracanthas; those 2” thorns can pop basketballs.
They can get tall, around 10 feet, but can be kept under 5’; their width is equal to their height. They have green leaves, and produce an orange berry in the fall.
So if you want that fortress feel without that penitentiary look check out the Barberries and the Pyracanthas.