Do you want a hedge with a dense base that will require regular topping, or a line of trees that won’t ever need to be topped? Both require very different management, and inappropriate management of either one will result in damage to the hedge and biodiversity.
It is important to understand how trees and shrubs grow in order to grow a hedge successfully. The central shoot of the tree grows up, causing the tree to develop into a single-bole stem with a canopy. This occurs as a result of apical dominance, which is when the main stem of the plant is dominant over the side stems.
When apical dominance is disturbed by pruning, lateral and dormant buds just below the cut fight to become the new terminal leader. Farmers need to bear in mind that hedges are managed habitats and need management to be maintained.
Native species
Farmers should plant species of native Irish provenance, meaning that the plants were grown in Ireland from seed collected from Irish trees.
Native Irish species are in tune with each other, with the timing of flowering suiting associated dependent species. Using native provenance hedging stock is also better for biodiversity as it reduces the health risk to our native trees and hedges.
What species to plant?
Trees and shrubs that tolerate trimming should be chosen such as the thorn species – whitethorn, blackthorn and holly. These are excellent for the structure in hedges and should provide the basis for all farm hedges.
Such species are the only ones recommended to take up the majority of species in topped hedges as they are also ideal to provide the occasional mature tree within the hedge without shading out and causing gaps as is common with larger hedgerow trees.
For a topped hedge, farmers should buy two-year-old bare-rooted whips, six plants per metre, which should be mainly whitethorn. However, once every 2m, replace one with another hedging species that tolerates trimming such as blackthorn, holly, hazel, spindle, guelder rose, dog rose and woodbine. Therefore, for every 100m of a new hedge, you need 550 whitethorn and 50 other species.
Cultivate the ground using a digger which will make it easier to plant.
Martin Crowe, pictured, planted a hedge last Christmas, and plans to continue to do this over the next few years. With the help of his kids over the holidays, Martin put in 350m of a hedge that was made up of mostly whitethorn, dog rose, guelder rose, blackthorn and hazel. The hedge was pruned near the end of March. Martin has now identified a further 750m of an area that he plans to put a hedge along over the next two winters.