Fruit trees are trained into particular shapes to make them more productive, easier to manage and better able to support heavy crop loads.
Formative pruning (also referred to as framework pruning) is carried out in the first three years of planting a young tree to create or ‘form’ the shape, and establish a framework of main branches.
When a young tree is first purchased, it may already have some branching, or it may be a ‘whip’ which is basically a long, straight stem with no branches at all. Occasionally a garden nursery will carry out the first year’s pruning to begin establishing a tree shape, either a vase form or a central leader form.
The central leader form is the classical ‘Christmas tree’ shape – conical, wider at the base and narrower at the top, with less space lower down where the longest branches are, and more space above. Most often, pears, almonds and occasionally apples are grown in this shape. The advantage of the central leader form is that it is a bit stronger than the more common vase shape, and can therefore bear slightly heavier crop loads. This form is not suitable for fruit trees that are very vigorous and which branch extensively, such as apricots. peaches, nectarines and Japanese blood plums, as the branches grow into a tangled mess.
By comparison, the vase form is the more common tree shape used for fruit trees, especially in backyard gardens. Being more or less a cup or goblet shape, with increased branching towards the top, a vase form has more space below the tree, allowing for the planting of small shrubs such as berries, taller herbs or companion plants beside the trees. This form is very universal as it can be used with any fruit tree.
So, where do we start when looking to select a young fruit tree?
Selecting a Young Fruit Tree
There are three important things to look for when selecting a young fruit tree, as no two trees are alike.
- A nice thick straight trunk (bud-grafted trees will always have a ‘bend’ at the graft junction).
- A good framework of branches (except if the tree is not an unbranched ‘whip’, which is common for fig and mulberry trees).
- An appropriate shape – either a central leader form, a vase form, a flat growing branched shape for espalier training or a whip which can be trained into whatever shape is desired.
Once a tree is selected, it will need to be pruned over a tree year period to establish its shape and form.
The Structure of a Central Leader Tree Form
The diagram below illustrates the shape of a central tree form. The trunk is tapered from the wider base to the narrower tip of the tree, forming a central leader, with branches radiating out from trunk at various levels, longest branches nearest the base, becoming progressively shorter towards the tip.
How to Prune a Fruit Tree into a Central Leader Form in the First Three Years
The central leader form is best for fruit trees whose branches have more of an upright growth habit, such as apples, pears, cherries, almonds, persimmons and European plums. The vase pruning form is used for trees whose branches naturally have a wide, spreading habit.
Training a fruit tree into a central leader form is a three-year process, which is described in detail in the steps below. Formative pruning (framework pruning) is carried out in late winter each year, for the first three years. New growth is pruned back to create further branching.
The aim of central leader framework pruning is to create a tree with a single vertical central leader, with layers of branches spaced approximately 40cm apart radiating out from it, to a height of around 2.5m (8’), or whatever height is preferred, lower or higher. The diagram only shows three branches per level for clarity but up to 5 branches can be grown per level.
To create the central leader form:
- Starting at the lowest branches, select 3-5 of the strongest branches which are evenly spaced around the trunk, and cut them back to approximately 20cm (8”) long. Make the cut above an outward, downward or sideways facing bud (but not an inward facing bud, see diagram below). The new branches will grow from those buds, in the direction that the buds are pointing.
- Create the next layer of branches approximately 40cm (16”) above the bottom layer, once again, selecting 3-5 of the strongest branches which are evenly spaced around the trunk, and cutting them back to approximately 20cm (8”) long.
- Prune out any other branches growing between the two layers of branches. Don’t cut of unwanted branches flush against the stem, make sure to leave the branch collar intact! See article Tree Pruning, How to Remove Tree Branches Correctly for further explanation.
- Repeat process to create as many layers of 3 to 5 branches up to a height of approximately 2.5m (8’), spaced 40cm (16”) apart, pruning out any branches between the layers.
- If the young tree has a long central leader with no branches at the top, prune off the tip bud, making the cut above a bud at a 45-degree angle, 6mm (1/4”) above the bud, angled so that water runs away from the bud, and not onto it. For more information on making pruning cuts, please see article – How to Prune a Fruit Tree, Step By Step. Cutting off the tip bud will induce the buds along the leader to shoot, forming new branches.NOTE: There are two ways to make this cut, either cut the tip bud off and see where the new branches sprout along the stem, or find a group of buds around 40cm (16”) above the highest layer, and prune above those. One of the new shoots can then be trained vertically to create the new leader, which can eventually also be pruned above a group of buds around 40cm (16”) above the highest layer to create a new layer. The process can be repeated until the desired tree height is reached.
- If the branches have any side branches, prune them back to half their length to an outward/downward/sideways facing bud as shown is the diagram to encourage formation of fruiting wood.
- Once the desired height is reached, prune off tip bud, which will cause the central leader to grow new shoots at the tip. Cut these new shoots back to a single bud each year to limit height.
How to Prune and Maintain a Central Leader Tree Form
The above process explains how the levels of branches of a central leader tree form are created. The levels of branches that are created have to also be pruned in late winter in the second and third years, and every year afterwards to maintain a manageable length and to renew fruiting wood.
- In the first year, branches are pruned to 20cm (8”) long to an outward/downward/sideways facing bud.
- In the second, third and following years, new growth is cut back by half to an outward/downward/sideways facing bud. Depending on length, as little as one-third or as much as two-thirds.
Never cut back to inward facing buds as the new branches will grow into the tree, ruining its shape and form. Inward growing braches also cross with other branches and rub against them, creating wounds in the bark which can become entry points for pests and diseases.
It’s important to not let branches grow too long on fruit trees, as the branches can break off under the weight of heavy loads of fruit. If they are left to grow too long, they have the potential to produce too much fruit and may break off.
If branches grow up rather than out in a central leader form tree, they can be tied to a wooden stake or a brick on the ground to gently train them outwards.