Summer Pruning

Authored by Jodi Roth.

It’s time for the final post of our 5-part pruning blog series!!

To review our previous posts, we did a quick intro to why we prune, then an in-depth look at spring pruning followed by a look at how to prune various berry bushes and vines. After that we looked at pruning an old, neglected apple tree.

Now we need to take a look at summer pruning; why and how it’s done!

Why Summer Prune?

Summer pruning is done with the goal of slowing down vegetative growth to then set your tree up for production in the following season. It’s all about energy management!

In the above photo, Steph stands beside a freshly pruned dwarf apple tree. Later on in this post you'll see the before and after side-by-side.

There are lots of factors that can impact a tree’s growth and fruit-bearing capacity, (such as soil nutrients, watering, etc.), however, we are specifically looking at summer pruning for control of a tree’s size, shape and fruitfulness. The following factors will help determine how much and when we do summer pruning:

• Age of your tree
• Vigour and precocity of the fruit variety
• Rootstock variety
• Best energy timing for your goals

Age of Your Tree:

For most young trees between 1-3 years old, it’s not recommended to summer prune at all, regardless of vigour, because you want to allow the tree to get established and use all those leaves to store lots of photosynthesized energy down in its roots for over winter and future vegetative growth. Then you’ll have choices for where to create structure/scaffolds in the following spring (revisit the spring pruning post if needed).

Meanwhile, on older trees, summer pruning is the key to slow down unwanted vegetative growth and shift energy towards the fruit. Your summer pruning will help you direct the tree towards more fruitful growth in the future as well as maintain its shape and scaffold layers; plus it’ll allow sunlight into the canopy to help ripen the current fruit crop that may be there.

Vigour and Precocity of the Fruit Variety:

First, let’s clarify what we mean by vigour and precocity. Vigour refers to speed of vegetative (leaf and stem) growth, while precocity refers to maturity and how quickly the tree produces flowers and fruit crops.

Depending how vigorous/precocious your trees are, you may choose to prune one more than another, or not do any summer pruning at all on a slow growing variety! Pruning out some of the summer growth slows the tree down because you’re removing green, leafy, photosynthesizing, energy-producing branches. In summer, the tree is focused on its fruit-set, leaf growth and fruit development so it will not be re-directing energy away from those things into re-growing more new wood, as it does with dormant pruning.

Rootstock:

Rootstocks can impact both vigour and precocity too, so it’s important to consider both your rootstock and your fruit variety. In particular, a rootstock tends to impact the tree’s height and lifespan (vigour) and how soon it bears fruit (precocity). Full-sized or semi-dwarf rootstocks tend to have lots of vigour but will take longer to mature, thus have less precocity. Meanwhile, dwarf rootstocks have lower vigour (smaller in height and shorter in lifespan) but higher precocity.

How does this impact your summer pruning?

You’ll take both the fruit variety and rootstock qualities into consideration when you assess what shape to maintain and when making decisions about what timing to choose. For example, you may choose to prune a full-sized or semi-dwarf tree a little more and a little later in the season (see timing section below for more on this) than a dwarf tree because you want to slow down the full-sized tree, and you know it generally has more vigour to apply from the rootstock. This would be especially true if you had a vigorous fruit variety grafted onto the full-sized rootstock, but then on the flipside, you may adjust that decision if you know the fruit variety is low vigour (slow growing).

Ultimately, most of the pruning decisions will happen naturally when you’re physically looking at the tree, but keeping the rootstock and fruit variety qualities in the back of your mind can help you understand why one tree is a lot larger than another tree of the same age.

Best Energy Timing for your Goals:

The timing of your summer pruning can also impact how energy will shift in your tree. You can take advantage of timing your summer pruning to maximize slowing vegetative growth (likely on an older tree) or strike a balance between promoting some new vegetative growth and promoting fruit (on a younger tree).

Summer pruning can be done beginning any time after petal fall (this is a term orchardists use to mark timing of orchard activities such as holistic spray or pruning by the blossom petals falling off, which varies tree to tree) up until mid to late summer or post-harvest for trees like cherries who’s fruit ripens mid-season.

However, a note of caution on post-harvest pruning:

If your harvest time isn’t until late-summer or onwards (apples, pears), the tree may struggle to heal its pruning wounds, and if young sprouts emerge they may get damaged by early frosts. While late summer pruning can be done, in our area it’s generally best to aim for summer pruning to be completed by mid-summer (rather than late summer) so that you don’t have to risk any wound-healing issues or early frosts damaging new growth before it has hardened off.

So how can timing impact your tree’s energy?

After petal fall, your tree will be prioritizing fruit set and the tree will still have a bit of energy left for pushing out new growth after you prune. Some new branches may still form and existing branches will still grow longer over the season, but you will have slowed your tree modestly.

Next, if you wait until leaves and baby fruitlets form, your tree will have expended a lot more of its stored energy into the fruit and leaves and it’ll have significantly less energy to expend on pushing new branches and little to use on extending existing ones. Pruning will be slowing growth moderately.

If you wait even longer, your tree will be further along in producing fruit and new vegetative growth will be slowed even more significantly. As mentioned above, cherries and other early-fruiting trees can be post-harvest pruned for the most significant slowing of growth because at that time the tree will have spent its growing energies and will want to conserve energy in its roots to prepare for winter dormancy. Pruning wounds will have ample healing time and any new growth will still have time to harden off. Meanwhile, other varieties such as apples and pears are best pruned earlier, before fruit harvest; with mid-summer being a good cutoff time so that they have time to heal/harden off and you still see a good reduction of growth because the trees are focusing on ripening their fruit and the branches/leaves they already have.

Now, let's review that. Looking back to the first paragraph in this section, what timeframe would you want to aim for if you wanted to balance between slowing growth just a bit, but you still want to see a few new branches and promote fruit?

What timeframe would you choose if you wanted to slow new branch growth as much as possible?

If you are mentally saying prune earlier for balancing and later for slowing growth as much as possible, you’ve got it!

So now that you know what to consider as you approach your trees, how do you carry it over into action with your pruners?

You will use the same key concepts as with winter pruning, focusing on creating the structure you want for your tree; see the dormant pruning post if you need a full review. In particular, remember the 1/3 rule about removing only approximately 1/3 (or less) of the tree. Both that and the pruning cut details (cutting above growth collars, using heading and thinning cuts) still apply in summer. If those terms are totally new to you, please go back to the post linked above to learn more! Also recall that if you need to remove larger branches, you should always cut back to a branch that is a minimum of 3 times the diameter of the branch you are cutting as mentioned in our old apple tree pruning post. Below are some photos of other notable things you may take into account when deciding what to prune during your summer pruning session.

Now, before we send you off, let’s also take a look at water sprouts, those vertical shoots that aren’t going to produce fruit and will shade out and weigh down the branches they’ve sprouted from.

We discussed removing them during dormant pruning, and we also mentioned that they can be trained to lay horizontally (laterally) to change them over into fruit-producing branches if desired. However, in older trees it can be very beneficial to remove water sprouts during summer pruning when the tree wants to focus its energy on fruit and leaves more than new growth. Keeping in mind the 1/3 rule, you can remove water sprouts as a large component (and in some cases it may be 100%) of your summer pruning if your tree has lots! If needed, leave some to be pruned out in the future as may be the case in a vigorous, old or rejuvenation-project tree.

If you need propagation material (dormant grafting or summer grafting), remember that the water sprouts are exactly what you want for that, and prune accordingly.

And if you have water sprouts that you want to train into lateral branches, you can absolutely do that as a part of your summer pruning care using tree training bands or your own ties (rope around a brick or stone, etc.) to gently weigh the branch down and secure it into the position you want. Remember that ties will need to be removed before they girdle the branch and monitor them regularly to ensure they don’t cause damage.

Finally, remember the weather before you prune! What might be a wonderful beach day is not an ideal time to be out putting pruning wounds on your trees. If the weather is 35°C or above, the pruning wound can be damaged by the heat (drying out) and sun (burning), which can leave the tree susceptible to other pests and diseases entering from the pruning wound. Planning your pruning during a cooler week or rainy/cloudy days will improve healing and probably be a bit nicer for you working outside too!

Let's take a quick look at the before and after of Steph's dwarf tree pruning below: You can see that the canopy has been cleared out around the bottom scaffold layer. In the top area, some new growth was left to take out at a future pruning because we were reaching the 1/3rd removed point where we wanted to stop.  

And with that, our final pruning post has come to a close. If you’ve been following along and have questions or comments, please feel free to share them in the post comments or send us an email or social media direct message. If you have a topic you would love to see us cover in a blog post, please also feel free to share that too – we have tons of ideas, but not always enough time for execution and if we know you’re interested, we’ll know what to prioritize next!

This 5 part blog series began by focusing on young trees and is intended to help new and intermediate growers who are beginning their orchard journey. Posts are linked below.

Post 1: Planning Your Most Important Spring Orchard Task

Post 2: Spring Pruning: Fruit Trees

Post 3: Pruning Berry Bushes & Vines

Post 4: Pruning An Old, Neglected Apple Tree

Post 5: Summer Pruning (that’s this post!)