I call this tree the Japanese Fuerte. I’d seen many pruned avocado trees, I’d pruned many avocado trees, and I’d read much about others’ pruning of avocado trees, but I’d never encountered an old tree that had been so consistently and artfully molded to a shape and size as this one. It was grown in the yard of a Japanese family living near San Diego. The day I met this tree was the day that affirmed what I had always imagined could be achieved over the long term by a visionary avocado tree pruner.
Why prune avocados?
We’re used to the idea of pruning other fruit trees, like peaches, but pruning avocado trees is not so familiar — for good reason. Unlike peaches, even if one never cuts a branch on an avocado tree, it can remain healthy and provide oodles of fruit for a century. (See the old trees at The Huntington, for example.)
But there are some good reasons to prune avocado trees, some situations where it’s advisable. I can think of three. One is to keep them down to size, whether in height or width. This was obviously the main objective of the pruner of the Japanese Fuerte. The tree had to be kept back from the fences and wall that surrounded it.
Another reason to prune is for balance. Some trees are determined to be lopsided, it seems. The danger of that is that they might fall over in high winds or under the weight of a lot of fruit. I have a Lamb Hass tree that insisted on leaning toward the south. I consistently cut back southward-aiming branches and after about four years it was filled out and standing up like a tree should.
Pruning low branches that interfere with sprinklers is also a good idea. This is something that mostly needs to be done with young trees, but it has to be done or else the low leaves can entirely block the sprinkler’s spray.
Beyond these three good reasons to prune avocados, don’t do much fiddling. Removing upright shoots (sometimes called water sprouts) or dead inner branches can be done, but is unnecessary.
Best shape for an avocado tree
So what’s the best shape for an avocado tree? There isn’t a single best shape for every tree in every situation, but there are some principles to keep in mind. The most important one is that lower and inner branches will become less fruitful and eventually die unless they get enough sunlight. This is why large avocado trees are like caverns, where the inside is nearly empty and most of the leaves and fruit form a dome.
Particularly if you want to keep your avocado tree smaller than it would naturally grow, then you’ll want to aim for a globe or fat pyramid shape. The idea is essentially to prevent the upper foliage from shading the lower foliage too much. Do this by making the top narrower than the bottom, especially on the north side of the tree.
An alternative that some have played with for avocados is the open center or vase shape that is common among trained stone fruit trees like apricots and nectarines. This shape just carves out a gap in the upper middle foliage so that sunlight can penetrate better there. Occasionally, an avocado tree will naturally become amenable to this shape by bifurcating its trunk down low. You may want to go with the flow and choose to shape such a tree in an open-center style if that’s the case. I have done so with my Reed avocado tree. (Here’s an article discussing open center pruning on avocados.)
In between the fat pyramid and open center shapes is the donut shape of the Japanese Fuerte. Its interior and lower limbs are still vigorous and fruitful because there simply isn’t a thick canopy above them.
Making cuts and the tree’s response
Cutting back to a lateral branch is best, specifically a lateral branch that is at least a third as thick as the branch you’re cutting. If you do this, that lateral branch is likely to take over the growing energy of the branch you cut, and it’s also likely that your cut will heal well, maybe even close up its wound entirely. Here’s an example of such a cut and response:
But sometimes avocados, more often than other kinds of trees, decide to send energy into a lateral branch growing somewhat below your cut. Don’t be surprised or dismayed if this happens. An example:
More to the point of why we’re growing an avocado tree in the first place, however: Will pruning an avocado tree reduce its fruit production? Yes, maybe. The bigger the tree, the more leaves and flowers and fruit it can produce. That’s the simple truth. But if you prune at the right time, your tree will barely skip a beat and still produce plenty.
When to prune avocados?
When is the right time? Significant pruning is usually best done in the second half of winter. That means from now, as I’m writing this in late January.
The reasons are that we’re past the time when a serious cold snap can damage your tree (thereby “pruning” it extra). Also, the tree is beginning to flower and grow new leaves, so as soon as you make your cuts the tree will begin filling in the gaps. Any branches that have been newly exposed to sun will likely be protected by foliage before the heat of summer threatens to sunburn them. Still, avocados being so sensitive, it’s wise to paint exposed branches anyway. (See my post, “Avocado trees get sunburned — what to do?”)
Furthermore, avocado trees create next year’s flower buds in the summer, so the tree will have the spring months to grow new branches and then initiate flower buds on them this summer, ensuring that the tree’s fruit production doesn’t skip a year.
Speaking of fruit, if you’re pruning a Hass or Fuerte or Bacon or other variety whose fruit is mature now, then you also don’t waste any of this year’s fruit. You eat the fruit that you prune off.
All that being said, if possible, it’s best to prune a little here and there to doing one big pruning in late winter. Nipping back a little branch that is going in a direction that you don’t like is best done as soon as you notice it so the tree can start growing in the direction you want sooner.
But what if an avocado tree has gotten away from you and it’s now 30 feet tall but you’d like to bring it down to 15? This is more challenging than maintaining a tree at 15 feet tall, but it certainly can be done. In fact, it’s done all the time in commercial groves in California.
Broadly, there are two ways to approach this. One is to stump the tree. This is drastic pruning where the tree is cut down to a stump of no taller than about five feet. All exposed bark must be painted. As the tree grows back over the next couple years, you then shape it and maintain it at your desired height. You’ll get no fruit for the first couple years.
I stumped this Sir-Prize avocado tree recently:
The second general method is less severe and involves cutting back one or two large limbs each year over the span of a couple years until your tree has been brought down to the desired height. You still have to paint any exposed bark, which can be difficult since the painting sometimes needs to be done high up in the tree. But the advantage of doing this is that you won’t lose all fruit for a couple years.
Spring and summer fruiting varieties
A final consideration is for varieties whose fruit matures in the spring and summer. Take my Reed tree as an example. It has a branch that is growing too far off to one side, imbalancing the tree. I want to cut it back, but the part of the branch I want to cut is carrying a dozen fruit. That fruit is the very reason the branch is leaning so horizontally.
Reed avocados in my part of San Diego County start tasting good in May, so I’m waiting until May to prune that limb in order to not waste that fruit.
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