Fruit Tree Pruning: Winter or Summer? Or Both?
Farmer Fred Garden Rule #8: If it works for you, fine. But keep an open mind.
In the Feb. 10, 2023 “Garden Basics with Farmer Fred” podcast (Ep. 252), we heard from Master Gardener and Landscape Designer Quentyn Young about the benefits of summer pruning of deciduous fruit trees, as well as the drawbacks of winter pruning. Quentyn’s primary reason for concentrating on summer fruit tree pruning? The chance of disease hitting open wounds in the winter time due to the seasonal rain. Those cuts heal themselves much slower in colder weather than if the cuts were done in the spring or summer.
But, as you may be aware in the world of gardening, there are multiple ways of achieving a successful harvest of vegetables, flowers, and fruits without appearing to be harming the plant. How many times have you heard a fellow gardener utter the phrase, “Well, that’s not the way I’d do it!” And they may be right, because they had success doing it their way.
As Farmer Fred Garden Rule #8 suggests: “If it works for you, fine. But keep an open mind.” If you're using safe gardening techniques that others might frown upon - and those techniques are working for you…well, who are we to tell you to stop? Still, new research, techniques or equipment may make your chores a heck of a lot easier and satisfying. Today's solution, after all, could become tomorrow's problem. Be open to change.
With that said, we present a couple of alternatives to fruit tree pruning that include good reasons for pruning in the winter as well as the summer.
First up: enjoy and learn from this winter fruit tree pruning video, presented by Tom Spellman and Phil Pursel of Dave Wilson Nursery:
Pictured is Chuck Ingels, the late University of California Farm Advisor for Sacramento County, and the impetus for the start and the development of the Fair Oaks Horticulture Center. Here, he is conducting a demonstration of winter fruit tree pruning (on a nectarine) during a Horticulture Center workshop.
Chuck also implemented at the Horticulture Center a radical (at the time) fruit tree pruning practice: “summer pruning”, to keep fruit tree height at about six to seven feet, making backyard fruit picking a no-ladder-needed event.
Here’s what he had to say about summer vs. winter fruit tree pruning, portions of which are in his book, “The Home Orchard”. Remember, this is a University of California publication, and its timing suggestions for pruning may reflect a USDA Zone 9 bias. Still, there is enough quality information about growing backyard fruits in this book that a grower anywhere can benefit, after adjusting for seasonal differences.
I’ve been doing a lot of summer pruning on different types of fruit trees. I’m convinced that it’s the best thing for nearly all species, and on espalier and fruit bush trees I do summer pruning exclusively.
The timing of pruning influences a tree’s response to pruning. Dormant pruning is the most invigorating because it allows the carbohydrates that the tree has stored in the roots and wood for the winter to be allocated to fewer growing points. Also, unlike summer pruning, dormant pruning does not remove actively growing and photosynthesizing leaves. Pruning in early spring also stimulates growth below the pruning cuts. However, pruning from mid-spring through summer reduces a tree’s vigor to some extent since the tree has already expended valuable carbohydrate reserves on shoot growth and leaf development. The removal of young leaves before they can contribute substantial carbohydrates to make up for the energy that has gone into creating them has a somewhat devigorating effect on the tree, reducing its overall growth potential. Because most fruit trees tend to grow too vigorously, summer pruning can have a beneficial effect.
Summer pruning, which actually is done any time from mid-spring through summer, typically is used to remove excessively vigorous shoots that shade lower fruiting branches. When you prune in summer, primarily using thinning cuts, you are able to prune very vigorous shoots without stimulating even more growth. Summer pruning of fruit bushes, however, does lead to vigorous shoot growth. In general, it is a good idea to do both summer pruning (in which you mostly use thinning cuts to allow more sunlight into the lower canopy) and dormant pruning. However, large cuts in the lower portion of trees should be avoided in winter and early spring in wetter areas because wood-rotting fungi may infect wounds. Such large cuts made low in the tree should only be made from late April through August, and never when rain is predicted.
If trees receive appropriate summer training and pruning, far less dormant pruning is necessary. Winter pruning, however, allows you a clear view of the tree’s framework in the absence of leaves. In winter you can remove any crowded or unwanted branches that were not adequately pruned during the growing season.
One notable feature about apricots and cherries is that they are susceptible to infection by branch-killing diseases, including Eutypa dieback and Botryosphaeria dieback. Infection occurs on wounds made during wet weather from fall through winter, causing severe gumming at pruning wounds and branch dieback. Because they are susceptible to these diseases, it is best to prune apricot and cherry trees after harvest in the summer (July or August) so that at least 6 weeks of rain-free weather are likely to follow the pruning. Pruning in August will result in less subsequent regrowth than pruning in July. Make sure to prevent sunburn by leaving enough foliage to cover limbs or by painting limbs exposed to hot afternoon sun with whitewash or a 50-50 mixture of interior white latex paint and water. If summer pruning is missed, prune in the late dormant season or early spring. These diseases are much less prevalent in very dry regions and in much of Southern California.
No matter which training method you choose, consider doing some pruning in the spring and summer to train young trees and shorten the time to full fruit production. When necessary, bend and stake shoots of young trees to grow in the desired direction during the spring and summer. Bending branches in this manner is a quicker way to develop the scaffold structure than heading the branches and waiting for new lateral branches to form.
Chuck was also one of the authors of the free University of California publication, “Fruit Trees: Training and Pruning Deciduous Trees”.
This publication may turn on the light bulb in your head to grow “fruit bushes” instead of “fruit trees”. Think about that. Instead of letting a fruit tree get 20 feet tall, why not limit its height to no more than you can reach while standing on the ground? Not only is it safer for the backyard orchardist, it also means you can grow more fruit trees in a small, sunny yard. And yes, you will still harvest enough fruit for your family and friends. This advice applies to newly planted fruit trees, which have been initially cut back to about knee-height.
“Fruit bushes” are standard (full-sized) trees or, preferably, trees on dwarfing rootstock that are kept small by periodic summer pruning. This method can work for nearly all fruit species. The beauty of this system is its simplicity and ease of management. Pruning begins in about late April or early May of the first growing season, when new growth is about 2 feet (60 cm) long. At this time, cut the new growth in half, aiming for a uniform, bushy appearance. Hedge-trimming shears may be useful in this. In about late June, cut the subsequent new growth in half. If new growth is vigorous, it may need to be cut once more during the season. These heading cuts promote an excess of branches, so thin them by removing some shoots to allow sunlight to reach the lower branches. If needed, thin out additional crowding branches in the dormant season when they are more visible.
In the second year, continue cutting new growth in this manner until the trees reach 5 to 7 feet (1.5 to 2.1 m) tall, a height at which you can easily prune the top. Pruning in subsequent years involves cutting off any shoots above the tree’s permanent height two to three times per year. Also, thin crowding branches, especially at the top of the tree, and remove unproductive fruiting wood in early spring when branches without flowers are visible.
Note that many of the pruning cuts recommended, including in the above video from Dave Wilson Nursery, are “thinning cuts” - the removal of an entire branch, cut back to near where it meets a larger branch of the trunk. “Heading” or “topping” cuts - where you’re pruning to remove height only - are used less frequently.
One nice feature of that free publication, “Fruit Trees: Training and Pruning Deciduous Trees”, is the inclusion of a “pruning glossary”, which explains the difference between heading cuts, thinning cuts, and topping.
One final piece of advice: no matter what season you are pruning a fruit tree, consider what will happen when bright sunshine hits the newly exposed trunk or lower branches in the center of the tree, that before may have been in consistent shade. One possible result: sunburn, causing cracking of the branches or trunk. Besides pruners, loppers, and a small saw, add a container of a 50-50 mix of water and white interior latex paint to your arsenal for tree protection. Slather it on those newly exposed branches!
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Fred Hoffman is also a University of California Cooperative Extension Master Gardener in Sacramento County.