in article , Keith D at
wrote on 6/4/03
9:27 am:

Hi all,
I can remember a few years ago a crime prevention officer mentioning
so called deterrent bushes that you can place around your garden or points
of possible entry - not doors :-) Can any of you recommend some thorny
plants/bushes fit for this purpose - is there any limit to the height that
they will grow or do they reach a natural peak ? Apologies for sounding a
bit daft but, as you can see, I do not know a lot about this subject.

Rosa rugosa, Berberis, Aralia Grevillea are 4 that spring instantly to mind.
A good thick, spiny holly hedge isn't exactly inviting! A Google search
might throw up more answers from previous, similar discussions.
And gravel around the house or garden perimeter is an excellent deterrent,
too. So is a small dog that barks at the slightest movement and wakes up a
bigger one that sounds more threatening!
--
Sacha
www.hillhousenursery.co.uk