Smallholders are always on the lookout for ways to improve their security and one option is to plant an impenetrable hedge, using shrubs that have thorns.
One of your first choices might be the Kei Apple (Dovyalis caffra), an evergreen shrub that grows to a height of 3-5 metres. It has the further advantage of bearing fruit, which is the size of an apricot with a citrusy sort of flavour and used to make jam. The shrubs are also planted around gardens to keep out animals. Kei Apples are quite slow growing, taking five to seven years to reach their full height and they do not do well in areas where there is frost. In rural areas the leaves are used as fodder.
Another shrub used in hedges is the Lemon Thorn (Cassinopsis ilicifolia), an evergreen with good leaf density and ornamental appeal. The sharp green spines might be small, but they act as a definite deterrent. One shrub can grow to 4metres high but also 4 metres wide and they can be trained into a hedge. They flower in spring and produce small orange berries from February to May. A wide variety of birds eat the fruit, but goats and cattle also like the leaves.
Searcia pyroides occurs all over South Africa. The name pyroides refers to the burning sensation caused by a prick from the thorns. It is sometimes known as the Fire-thorn Karee. It is a hardy, frost-resistant plant and is well suited to Highveld plots. It grows to a height of 4.5 to 5 metres and spreads well when pruned into a hedge. Shrubs can be planted 2 to 4 metres apart. The fruits are round and small, white and red when ripe and usually grow so abundantly that they cause the branches to bend. The fruit is edible, with a pleasant, sweet-acidic taste and much-loved by birds.
S pyroides is not to be confused with the Yellow Firethorn (Pyracantha angustifolia or geelbranddoring) which many of us already have on our plots. Unfortunately this shrub has been declared a Category 3 invasive plant, because it competes with and replaces indigenous species. The shrub has stiff, spiny branches, with white flowers from October to December and orange-red or orange-yellow berries. They do form an impenetrable hedge, but one is no longer allowed to propagate them.
In warmer areas Bougainvillea can be encouraged to form a hedge and you might also look at bigger aloes.
In many parts of South Africa the Krantz Aloe (Aloe Arborescens) is planted around kraals as a beautiful living fence.
But if you really mean business, you should plant the Spike Thorn (Gymnosporia buxifolia /Maytenus heterophylla). It might not be as pretty as the other shrubs, but the spikes will certainly do some damage to unwelcome visitors. It is faster growing than the likes of the Kei Apple or the Natal Plum which are the traditional choices for hedges. It responds particularly well if you feed, mulch and water it to speed up growth.
You might also consider using trees as part of your security programme. The Buffalo Thorn (Ziziphus mucronata or Wag-‘n-bietjie) and various examples of acacia trees are not easy to climb, due to their spines.