Undoubtedly the plant that makes up the most miles of hedging in the UK is Hawthorn or in Latin, Crataegus monogyna. It’s the farmers’ friend being completely safe for animals to chew on – not that they tend to because it’s very thorny. Hawthorn hedging plants are native to the UK and do well in all soils and almost all conditions other than waterlogged soil – obviously in some areas there are plants that are better suited – near the coast for example, we’d generally recommend Blackthorn instead, or in wetter soils, Alder or Willow make good native hedge alternatives.
As well as separating farm fields, Hawthorn is popular in an urban setting too. It brings a great deal of wildlife into the garden providing wonderful creamy white flowers in May (hence it’s alternative name of May Blossom), big fat juicy haws drip off the tree in autumn (the hedging you’ll see from the car window on motorway journeys that look so heavy with red berries that the whole tree takes on a red tinge) and the prickly, woody stems provide a sanctuary for small creatures.
I’d say its drawbacks are that it tends to be one single stem – even the bare root transplants (2 years old up to 5 or 6 years for the 2m high plants) are not particularly bushy but we also do a multi stem Hawthorn bare root at about 1m in height which was severely pruned in the year before being sold to encourage bushier growth. We also use this technique on some pot grown plants to develop a bushy plant at about 1.2m in height usually in a 5L pot. On the other hand, you can do this yourself – buy seedlings (grown from seed sown in February and harvested the following winter) which we do at 40/60cm height and also 60/90cm height, and chop them back by half and they’ll reward you with bushier growth avoiding the pitfall of a lovely Hawthorn hedge which is gappy at the bottom.