Posted: 22/08/2013 at 11:35
You need something spiky to deter unwanted visitors and vandals so I would suggest pyracantha which is evergreen, thorny and has spring blossom and autumn fruits to feed and attract wildlife such as insects and birds.
It can be grown quite narrow and encouraged to spread upwards and across and you can choose form varieties with red, orange or yellow berries though the birds will like the red and orange best.
You will need to enrich and improve the soil with plenty of well rotted or bought garden compost and maybe some well rotted manure or just pelleted chicken manure before you plant anything.
Pyracantha maidens or small shrubs can be bought quite cehaply and the best time to plant is between mid September and the end of November which give sthem plenty of time to get their roots established before the spring surge of growth and blossom. Soak the pots in a bucket till no further air bubbles appear and water again after planting. prune any stems heading away from your wall and into teh walk space then watch them grow.
Yo may need to think about installing some tall posts and wires to train the branches across to form a solid barrier when they get above wall height. Smaller plants will get there faster than ones that are already tall and mature as they settle in better.