In its early years a tree may need some formative pruning to encourage it to develop a good shape. Removing some of the lower branches is the most common operation. Remember that a branch only 0.5m above ground in a young tree will still be only 0.5m above ground when the tree is mature.
You should avoid pruning until the tree has been in the ground for at least a year. Immediately after being planted the tree is quite stressed enough without further damage.
BS 3998 (2010) states; “The main aim of formative pruning is to produce a tree which in maturity will be free from any major physical weaknesses and which will complement the management objectives for the site.”
It then goes on to say…
“If, in order to influence the structure, shape or size of a tree crown, formative pruning has been started in the nursery, any pruning at or soon after planting should be kept to a minimum in order to retain an adequate leaf area. Formative pruning should normally be resumed three to five years later, but if the tree has been allowed to develop an unsuitable branch structure, some of the branches may be shortened or removed at an earlier stage of establishment. The early removal of all the lowermost branches should, however, be avoided if possible, as it could impair the development of a sturdy taper in the stem.
If branches need to be removed or shortened to deal with undesired patterns of growth, this should be done in stages so as not to remove too much leaf cover at any one time. Ideally, none of the selected branches to be removed should exceed 20 mm in diameter at the point of attachment to the stem. At least two-thirds of the height of the tree should always consist of live crown.
Within areas of high usage or formal plantings, potentially weak unions in young trees should be managed so that only one dominant stem or branch continues to grow from such a union. Where the total removal of an unwanted co-dominant stem or branch would create a large wound, it should instead be shortened, thus causing it to lose dominance.
NOTE 1 Failure to manage co-dominant leading shoots might eventually lead to compression fork weakness and thereby necessitate premature felling so as to safeguard people and property.
If two branches are crossing each other and likely to rub together, one of them should be removed or cut back so that further contact between the branches is avoided”