Pollarding is an intense form of pruning.  It should be done initially when the tree reaches a desired size, and then  continued each year. This technique encourages full and healthy tree crown growth and is  useful for managing trees that grow near electric or telephone wires or that cast too much shade.

It takes training, skill,  and experience to pollard a tree. Surrey County Council's web site warns,  "The effects of pollarding are potentially catastrophic to trees if applied inappropriately and can permanently ruin valuable specimen trees."

The annual pollarding season is between October and February when growth of deciduous trees lie dormant. The Royal Horticultural society suggests the following trees are suitable for pollarding:

• Ash (Fraxinus)
  
• Common lime (Tilia × europaea)
• Elm (Ulmus)
• Elder (Sambucus)
• Gum (Eucalyptus)
• London plane (Platanus × hispanica)
• Mulberry (Morus)
• Oak (Quercus)
• Some species of Acer (A. negundo and its cultivars)