Pruning Apple Trees
Sun is finally on the forecast this week and I’m feeling itchy to get outside and work on our perennial gardens including the fruit trees. Pruning is an annual job that I enjoy as both a meditative and artistic practice. I am a multi-tasker in the garden and will sprinkle the pruning chore over the next six weeks as I make my way through the orchard, berries and herbs. Join my journey as I write about the process including how to prune new fruit trees and thornless blackberries in the coming weeks.
Why prune your trees?
There are several reasons to prune your trees including to increase air flow and sunlight to fruiting areas. The increased air flow will protect your trees against disease. Sunlight will better penetrate the canopy of the tree and produce better fruit. Removing excess non fruiting branches also concentrates the tree’s energy into the fruiting wood.
Fruit trees are also pruned to establish a strong framework and maintain a shape that is conducive for fruit production and ease of harvest. All of our apple trees have been shaped in the standard vase shape with open centers. Most of our trees are also on semi dwarf root stock and we prune to keep them short enough so there is no need for ladders during harvest.
Keeping it Clean
It is important to clean your tools between each tree so you don't spread disease, like fire blight, between trees. I carry a small jar of isopropyl alcohol with me into the orchard and dip my pruners, allowing them to air dry between trees.
fruiting spur above
Fruiting Spurs vs Terminal Fruiting
Fruiting spurs are short stubby lateral branches that produce fruit year after year on apples, apricots, cherries, pears and plums. Peaches and nectarines produce flower buds on one year old shoots. It is important to observe your tree closely and identify the flower buds and where they occur. Flower buds will be much fatter and fuzzier than vegetative leaf buds. If you cut off too many of these then your fruit quantity will be diminished. This is not necessarily a bad thing and could direct more energy to the buds you leave, producing larger fruit of higher quality.
For apples specifically, fruit can be borne on either type of bud, terminal or fruiting spur. Fruiting spurs can produce fruit after year two and for 5-10 years thereafter.
Thinning vs Heading Cuts
There are two main types of cuts you will make on your trees.
1. Heading cuts shorten branches and remove the terminal or apical bud. This is the new growth bud at the end of a branch. Depending on the type of fruit tree this can either be a leaf bud or a flower bud. Heading cuts can help limit the height of your tree. These cuts are made about 1/4 inch above a lateral leaf bud pointing in the direction you wish to encourage growth, typically pointing outwards. See the photos below!
Heading cuts usually result in branching from the lateral buds under the cut. It is important to understand where the flower buds are on your tree before making too many heading cuts. Apples and pears usually flower from long lived fruiting spurs while peaches and nectarines flower on the terminal bud of last year's growth.
2. Thinning cuts remove entire lateral branches. These can serve to open up the interior of a tree and are used to maintain shape. We also use this cut to trim off vertical watersprouts that tend to go straight up. It is important to trim off the sprouts since these just suck energy from the tree and shade good fruit production areas. When making thinning cuts do not cut into the main branch. Be sure your cut is about 1/8-1/4 inch above the 'collar' where the lateral branch you are cutting grew from the main branch.
Principles of Pruning
Rather than hard rules, pruning is based on a set of guidelines. Different cuts result in different outcomes but as long as you are conservative, don't cut more that 10-30% of growth, your tree will be fine.
1. Cut away dead and diseased wood. This is where I always start with any fruit tree. Scan the entire tree for dead branches or those with visible disease. If the branch is indeed diseased you will want to be sure to remove it from the orchard. We send all our prunings to either the burn pile or a long term wood compost pile. If it is diseased it definitely goes to the burn pile.
2. Prune back branches that are crossed, sprouting straight up or headed down. Fruit production on apples and pears is best on nearly horizontal branches and poorest on vertical branches or those headed down. Crossed branches are too crowded and will reduce air flow and increase shade. Be sure to prune any sprout from the main trunk of the tree including the area below the graft line.
3. After making the above cuts, focus on each main branch in turn. Decide if it needs heading back. I usually head back the leaders on my apple trees each year to keep my trees at our ideal height- no ladders needed. Then I look down the branch for any crowding and make thinning cuts from there. Often after I have cut out the watersprouts, dead wood and anything crossing, the job is usually done.
Timing is also important. Most folks prune in the winter months when trees are dormant. It is also possible to do light pruning in the summer, especially to cut out water sprouts that may be over shading fruit production. If you are doubtful about how your tree produces fruit you can wait for flowering in the spring and then make your cuts as well. This way you can be sure about where your tree flowers before cutting.
I hope all this information helps! Take your time and realize that you can't really mess it up. Fruit tree pruning is one of those skills you will acquire only by doing.
Let me know if you have any questions and have a good holiday weekend. Check out the photos below to see the different types of cuts.
PS. Since we are talking apples I've included our apple pie recipe!