Various barriers to deter intruders have been used for centuries from the building of moats and walls to security lights and CCTV cameras. One form of defensive barrier which has stood the test of time, can be very economical with a little patience and be aesthetically pleasing is a Thorny plant. Once a plant of a prickly or thorny nature has reached maturity it can present one of the most formidable of obstacles. There is an abundance of choice when it comes to selecting the best plant to either, plant as a hedge, to climb up wooden panels, fences or walls, blending in with its surrounding landscape but still guarding the home.
Farmers have been using thorny plants for many a year to keep livestock in their proposed fields and delineating boundaries, mostly planting purely Quickthorn or a Native Hedgerow Mix where a large percentage of the mix would normally be Quickthorn and Blackthorn. If requiring an impenetrable hedge, planting can be done either side of wire netting growing through the fence to create an even stronger barrier. Foundation planting around the edge of a property especially under windows is also an excellent deterrent and can be extremely pleasing to the eye with colourful flowers and berries. Plants like a variety of Berberis with its fearsomely sharp thorns, Mahonia with clustered racemes of yellow flowers above tough spine toothed leaves or Rosa Rugosa with pretty red or white flowers would be ideal for this kind of use.
The evergreen plant Pyracantha with its abundance of sharp thorns, lends itself to being trained along fences and tied to walls, and would be virtually impossible to climb up or over without a fair amount of injury. With an abundance of colourful autumn berries, it is very pleasing to the eye and is also a great provider of food and habitat for. If planting any intruder deterrent hedge, possibly one of Holly, it is recommended to keep it at around 1 metre in height so intruders are unable to take cover behind it.