The reduction in the density of the tree canopy by the removal of epicormic growths and branches from within the crown, is called Crown Thinning.

Light and air can then circulate more freely through the tree, reducing the effective sail area of the tree, and therefore its resistance to extreme weather.

The process will first of all focus on any damaged limbs, or limbs showing a decline in health or are diseased, plus the removal of crossing branches within the canopy and any branches with acute crotch angles. Next, we would look to thin out the remaining branches so as to give an even, balanced appearance. As it is the foliage of the tree that provides the ability for the tree to photosynthesize (the formation of organic chemicals from carbon dioxide that all plant life need to live) no more than 25% of the foliage would normally be removed in a single operation. If further thinning is required, this is best done in one or two growing seasons time.