As a General rule when pruning any tree remember the 3-Ds- Dead, Diseased and Damaged. This wood should be removed first then crossing or rubbing branches. Never remove more than 1/3 of the tree’s branches. Trees that flower in the spring should be pruned shortly after they are finished blooming. An example is apple trees. Summer flowering trees can be pruned in late winter or early spring.
Evergreens generally need little pruning. To limit growth for pines its best to trim half of the candle off before the new growth has hardened off. After spruce caps have emerged fully clip off 1/3 of the growth. Doing this before mid summer will allow for new buds to form for next year, and will also make the tree bushier.
Deciduous Birch and maple trees are best pruned after they have fully leafed out in the spring (usually July). These trees have high sap flow in spring and will ‘bleed’ when damaged making them unsightly.
Elm trees can only be pruned during winter to prevent the spread of Dutch Elm Disease. (October 1 to March 31). Most other trees can be pruned in late winter or early spring while dormant.