On August 15, Vor Hostetler, VIFC Program Chair, organized a two orchard Summer Pruning Workshop at 204th & Vashon Hwy, the green former school district admin building, and at Dr. Bob & Carol Norton’s home on Maury Island. We watched, learned and then practiced hands on summer pruning techniques. Specifically, we learned that summer is the time to remove anything diseased and to take unwanted height out of a fruit tree never taking more than one third of the tree’s canopy. This has the added benefit of getting the fruit that is too high to harvest! “Summer, top down and winter, bottom up” became our mantra that afternoon. Enjoy the photos and the following Summer Pruning tips from Dr. Bob!
Summer Pruning – Principles and Practice
Vashon Island Fruit Club July 14, 2012
The traditional time for pruning fruit plants is in the dormant season, when storage reserves – sugars and starches produced in the leaves during the growing season – are stored in the roots and stems, ready to produce the vigorous flush of growth in Spring. Hard pruning or topping of trees in the Winter results in excessive vigor, often referred to as water sprouts, resulting in an unsightly tree, loss of fruit and an increased need to prune in the future years.
By pruning a healthy tree in mid-summer, July and August, when the tree’s storage reserves have not yet been replenished through photosynthesis, we can overcome the problem of excess vigor. Summer Pruning can act in a way similar to the effect of a dwarfing rootstock: reducing height, opening up a tree to better sun exposure, help coloring of fruit and reduce the need for future dormant pruning.
Pruning at times other than the dormant season can be employed for other reasons. For example, early flowering fruit plants like peaches, apricots and even plums can be pruned in late spring, May or even June, after fruit set. This can help get a better fruit crop, which in this cool, humid region may be the difference between some fruit and no fruit.
Young trees, especially peaches, plums and apricots can make excessive new growth, which may not be fruitful the following season. If you notice new growth in the center of the tree growing three to four feet by mid July, it is a good idea to either thin out the over vigorous branches or at least head them back.
Fruit trees trained to an espalier system need summer pruning to control excess vertical shoot growth and actually stimulate fruit bud formation.
Trees that have been topped the previous dormant season need summer pruning of the water sprouts, usually by hand removal when they reach 12 inches or more. Some shoots, particularly those that grow in a more horizontal direction, should be left to become fruiting branches in the next year or two.
How does one determine how severe the summer pruning cuts should be? First, look at the tree critically. Is it totally healthy, making an average of at least 6 inches of new growth annually? If not, prune modestly if at all. Weak trees should be pruned in the dormant season and perhaps receive fertilization, weed control or pest management to improve their vigor.
If the tree is healthy but just too tall or too dense, one can take out up to one third of the total canopy volume, concentrating on a few large cuts that reduce the height and open up the canopy. Don’t worry about drooping branches that are better removed during the dormant season. Try to cut back to branches of a similar diameter and avoid cutting branches leaving a horizontal would. No pruning dressings should be used with either summer or dormant pruning. Healing of the wound will commence immediately if left to dry naturally.
- Don’t summer prune weak trees.
- Remove excess growth to open the tree to light and reduce disease potential.
- Prune sweet cherries just after harvest (July).
- Don’t prune after Sept 1, unless there is a good reason (broken branches or disease).
- Avoid heading back pear trees until they are producing a crop that naturally bends the branches.
- Thin excessive growth (more than 2 feet in length) in peach, plum or apricot.
- Grape shoots can be headed after they have produced 10 leaves. Non-fruiting shoots can be removed.
- Prune male Kiwis right after flowering. Prune Kiwis similar to grapes.
- Prune fruiting canes of raspberry right after harvest, same for blackberries.
- “If in doubt, thin it out.”