This article describes how to stake fruit trees and which fruit trees will require staking.
Temporary tree stakes
A temporary stake is a wooden or metal post, often planted at a 45 degree angle to the tree it is designed to support, and fixed to the tree at a height of about 1m / 3ft. Thinner more flexible posts may also be used, even including thick bamboo canes. A small vertical stake can also be used as a temporary stake.
Temporary stakes are used to support trees which will eventually become free-standing trees once they have grown sufficiently. The purpose of a temporary stake is to hold the base of the tree in place whilst the roots establish themselves and the main stem of the tree thickens. A temporary stake is usually needed for the first 3-5 years of the tree's life, after which time the tree should have become self-supporting.
The temporary stake is usually fixed to the tree quite low down the stem so that the top of the tree is free to sway in the wind. It is the pressure of the wind which encourages the tree to thicken its stem, so it is important that the temporary stake allows the stem and aerial parts of the tree to flex in the wind.
Permanent tree stakes
A permanent stake is usually a thick treated wooden post, about 2m - 2.5m / 6ft - 8ft in height (or more), which is banged into the ground vertically beside the tree. (In fact usually the stake is planted before the tree). Permanent stakes can also be made of metal. In commercial orchards the stakes may be thinner but in turn supported on a strong wire trellis. In all cases the permanent stake forms a rigid inflexible support for the tree.
A permanent stake has a very different role to a temporary stake. Whereas a temporary stake is there to encourage the growing tree to thicken its stem and eventually become self-supporting, the permanent stake is designed to take-over most of the load-bearing role of the main stem of the tree. This means the tree puts less of its energy into growing a thick trunk to support itself, which means more energy for fruit production. The stake has to be permanent because if it is removed the tree will simply collapse.
Permanent stakes or some other permanent support are always needed for trees grafted on dwarf rootstocks, because these rootstocks are generally too small to support the tree in windy conditions.
Permanent stakes are a standard feature of most commercial orchards, and are particularly effective when the tree is trained with the central leader retained (and tied on to the stake). This form (often known as a spindle-bush) is very productive, and allows light to enter the tree which enhances fruit quality, as well as encouraging the tree to start fruiting much earlier in its life. The benefits of the permanent stake and the central-leader tree forms are equally applicable to the garden situation, especially for apple trees and pear trees.
It can be seen from the above that permanent stakes are almost always associated with dwarf fruit trees, since vigorous fruit trees will not need staking. However, if you are planting vigorous fruit trees in very exposed windy locations, you might also decide to use permanent stakes. In this unusual situation you would probably not plant the stake vertically, but would plant it at an angle - as you often would for a temporary stake - aligned with the prevailing wind. This is will reduce the wind pressure on the stake, ensuring that it stays firmly in the ground to suport the tree.