Perimeter hedge

Sites
http://www.hedgesdirect.co.uk/acatalog/common_hawthorn.html

https://www.hedgeworx.co.uk/hedging-plants/

http://www.ehow.com/how_5580240_grow-hawthorn-hedges.html

Indian Hawthorn
http://www.ehow.com/info_12316772_indian-hawthorn-tall-hedge.html Indian hawthorn (Rhaphiolepis umbellata and Rhaphiolepis indica) is the common name give to two closely related members of the rose family. Both are broadleaf evergreens, hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10. Both can be used for hedges. Available cultivars run the gamut from short (2.5 feet tall) to much taller (8 to 10 feet). "Best" is a relative term, but several cultivars stand out for size, beauty and disease resistance

http://treesandshrubs.about.com/od/commonshrubs/p/Growing-Indian-Hawthorn-Rhaphiolepis-indica.htm Get the tall variety, 5feet is not enough in South-Africa, Bougainvillea makes a larger bush.

links
http://www.plantdatabase.co.za/crataegus_douglasii

Boxed hedging
http://www.stakehillnurseries.co.uk/48-hedging-plants The evergreen Laurel's to the much loved Hawthorn and Beech hedge plants that attract many wild bird species. The fastest growing (and most popular) hedging plant is the Leylandii. This is available in either gold or green, they can be kept pruned to keep it to your ideal height. PLEASE SELECT ONE OF THE CATEGORIES BELOW.

Bougainvillea varieties
http://www.doityourself.com/stry/knowing-the-different-bougainvillea-varieties#b

dd
Plant bougenvillas, Hawtorn etc. at 1m spacing around the farmhouse. Make cutlings directly from the bougenvillas and propagate it besides the BG bush it was taken from. top to prevent intrusion over the topl.
 * Double gates with metal spikes on the top of the gates and water canon(http://en.wikipedia.org/wiki/Water_cannon) on
 * Embed the steel gate inside concrete.

The criminals are infiltrating estates and open streets by operating from a designated house and then jumping over the walls. Remove all the plants and propagate Kai-appel(hundreds) on both sides of the wall. If a crime situation is out of control and your neighbor will cooperate then a perimeter can be secured.