Fruit Tree Pruning

Pruning fruit trees is fraught with the turmoil of a thousand different philosophies.  This is an attempt to reduce the complexity and ambiguity of all those approaches into a single methodical process that works.  It is intended to take the guesswork and trepidation out of the process and give me a straightforward plan.

This process approaches the tree as one would an espalier or bonsai tree.  Trees are infinitely malleable.  With the proper insistence, they conform to your reasonable expectations.  This is not a philosophy that feels that it is somehow immoral to keep a tree severely pruned to be short, or to have an open center, or to train opposing branches along a fence.  Instead, we want to have a clear idea in our minds of what a "finished" tree should look like, and we prune it to make it conform to our growing space.

1.  We want our trees to be short:  between 4 and 8 feet tall. Any taller is excess growth and should be trimmed away.  Typically, you would prune the tree to the 6 foot height and it will grow another 6" - 18" during the course of the year.  This new growth will be pruned back to 6' each year.

Fruit trees can be even shorter, as low as 3-4 feet in some gardens, yet still producing fruit every year.  We have to understand that this is a paradigm shift away from American farmland style fruit trees with the big old apple tree that grew 30' tall.  It represents a fundamental change in our approach to "fruit trees" and one that has been practiced in French and Japanese gardens for centuries.  Just as we might trim boxwood hedges or strawberry beds, we prune trees to enhance their health and productivity and usefulness.

2.  Use a set of rods for measuring.  You frequently need to know the measurements of your trees:  total height at 6'; scaffold limbs at 3' with secondaries at 2'. The height of a tree can be illusory and deceptive, and it has a way of creeping up out of control.  Sometimes the clearest way to see exactly where 6' is, is to stand up a 6-foot rod next to the tree.  Then you will discover what you were calling  a 6' tree is actually 7 and a half feet tall.  These rods will help with the key pruning cuts you need to make in the central leader, and the scaffold branches.  And they will help you each year as you prune back the exuberant growth that will threaten the compact form of your carefully tended fruit tree. 

2.  Consider using a 12" raised bed in wet soils.  For the smaller trees that we are planting, use a 4'x4'  raised bed.  This will help with poor drainage and disease, as well as facilitating netting to repel squirrels.

3.  Under the tree should be mulched.  Don't let weeds and grass grow up under a tree, robbing it of moisture and nutrients.  Instead, cut the grass as low as possible and then cover with 4 inches of mulch.  This could be chopped leaves, commercial bark, grass cuttings, or any suitable substitute.  Each year, you should continue to add to the mulch, as it composts and adds nutrients to the soil. Many growers use nothing more than mulch and compost to fertilize their trees.

Some growers prefer to add 1 lb of "low-nitrogen" fertilizer to the area before mulching.  Nitrogen fertilizer will only add to the growth of the tree, something that we are trying to minimize.  Trees fertilized with nitrogen grow branches and leaves, and do not put much energy in to fruit production.

Also remember that your trees will be maintained as 6 feet tall or less, so don't follow recommendations for a 15-20' tree.

4.  Decide on the profile of your tree.  Trees can have a central leader, have an open basket, be espaliered to a fence or have a shrub-like habit.  Each of those is an option depending on the space in the garden you want to fill, but also influenced by the type of fruit tree that it is:  apple and pears favor a central leader, while stone fruits like peaches and plums favor an open basket.

While there are similarities, the profile helps determine the steps in caring for the tree.

5.  Trees should be pruned in the summer.  Trees pruned in the winter will always result in vigorous and upright growth, both things that you do not want in your fruit trees.  Trees are pruned around the summer solstice, June 21st (or 20th in leap year).  This is after the spring growth has occurred and while the tree is beginning to become dormant in the heat of the summer.

Pruning while there is fruit on the tree will identify the type of wood that the tree uses to set fruit.  These could be fruiting spurs, or 1-year wood, 2-year wood, etc.  You want to prune away the new year's growth of green, without losing the established fruiting wood.

Trees can and should be pruned multiple times during the summer.  Pruning three times may be the easiest way to manage unruly trees.


Training the tree growth.

Central Leader:
The top of the the central leader should be trimmed at 6' in height.

Identify two whorls or levels of branches, which I call tiers.  The lowest can be 2-3' above the ground, and the second level will be 4-5' above the ground.

Within each of the two levels, identify 3-4 scaffold branches.  Make thinning cuts to trim away all other branches than these 6-8 branches from the central stem.  Scaffold branches should be more horizontal, at a 60-80 degree angle with the trunk, with a slight rise, not sagging below the horizontal.  Branches that  make a very acute, narrow angle with the trunk are unsuitable and should be rejected.

Trim these scaffold branches at 3' from the trunk at a upward and outward facing bud.  The next year, two buds should form a Y behind the pruning cut.  Allow these secondary branches to grow, trimming away all other wild growing branches.  These secondary branches may curve upward as well.  Don't allow them to grow longer than 3 additional feet.
 
This creates the basic shape of the tree:  At the first tier, which is the lowest level:  cultivate three primary scaffolds at 3' each ending in two secondary scaffolds, branching and curving upward.  These secondaries are pruned at 2'.   You may want to label your scaffolds with forestry flagging or other light and flexible marker to allow you to always easily identify the most important branches.  From these secondaries, fruiting wood can branch off, but never for more than 6 inches.

For the second tier, the expectation is that the branches will be shorter overall. Scaffold branches are two feet long and secondaries are pruned to 1.5 feet.   For central leader trees, the total height is never greater than the 6' of the central leader.  All scaffolds and secondaries are trimmed to be lower than the central lead. 

Annual pruning.

Open Basket:
Trim the main stem at 18 - 24".   This will cause bud to form and create scaffold branches very low to the ground.  Select 3 of these to be your primary scaffold. Allow these to grow three feet and then use a heading cut to prune them.  This created two secondary scaffolds that will curve upward.

Because the primary cut to the main stem was so, low, we can now allow the secondary scaffolds to grow longer; an additional 3'.  This may put the top of the basket at 5-6' at this stage, where we will prune all secondaries.

Remember the length of the branch and level of the foliage controls the thickness of the trunk.  Keep the main scaffolds short and limit the growth of branches to only those primary and secondary scaffolds you have selected.