Pruning Olives for Drought Resilience: What I Got Wrong

In my second year back on this land I took a saw to a hundred neglected olive trees and cut roughly half the canopy off most of them, in three weeks, with total confidence. Pruning olives for drought resilience is the right idea, but almost everything I believed about how to do it was wrong, and the trees spent the next two years telling me so. What follows is what replaced it.

What this covers

Why the open-vase shape I read about was the wrong target for old trees on shallow soil
The one question that decides how much to remove, which has nothing to do with shape
What a seventy-year pruner told me that no book had
How I work now: little, annually, and never touching the central leader
What I still get wrong

The advice I followed

Every guide I read said the same thing. Open the centre. Remove crossing branches. Let light and air into the middle of the tree. Aim for a vase.

So that is what I did in 2011, on trees between thirty and a hundred and twenty years old that nobody had touched in a decade.

Three mistakes, and they are the mistakes everyone makes.

I cut too much in one season. By my estimate I removed around half the canopy on many trees. A tree is not a machine you tune in one sitting. Its root system is balanced against its canopy. Take half the canopy and the roots find themselves with surplus capacity, and the tree puts everything into rebuilding leaf area — water sprouts, that is, exactly the growth I had set out to remove.

I opened the centre on trees that did not want an open centre. These were old trees that had found their own framework over decades. I went in and removed the central axis from some of them, to “open them up”. The result was a tree forced to rebuild from the sides, with vertical sprouts that never fruit.

I treated a hundred trees as a hundred copies. They are not. A century-old tree has a history — old cuts, fire damage, a lean towards light — and its shape is an answer to that history.

The next two years the crop was very poor, and the trees produced a volume of water sprouts I was still clearing years later. I had created precisely the situation I was trying to avoid: an intervention that generates the need for the next intervention.

The question that actually decides it

The real insight did not come from a book. It came from Thanasis, who is eighty-four and has been pruning olives since he was fourteen.

I asked him once how he decides how much to take off. He did not give me a percentage. He said: look where the rock is.

Then he explained that on the shallow plots he cuts more, and on the deep ones less. Not because one tree is stronger, but because, as he put it, the shallow ground has nothing to feed it in August.

That is the whole principle in a sentence, and it took me years to arrive at it on my own.

Pruning here is water management. A canopy transpires. In a climate with four rainless months, on soil twenty-five to fifty centimetres deep over limestone, the canopy a tree can sustain in July is smaller than the canopy it can build in April. Leave it, and the tree goes into stress every summer.

This is not about shape at all. It is about the ratio between transpiring leaf area and the water that particular patch of ground can supply. That number is not in any book, because it is different for every tree on the hillside.

It also explains why pruning pairs so well with earthworks. Reducing what the tree demands is one half of the problem; increasing what the ground can hold, through swales and berms, is the other. I do the earthworks in autumn and the pruning in February, and the tree meets spring with both.

What I do now

I prune a little, every year. Instead of a large intervention, I remove a small proportion annually. The tree does not panic, does not throw sprouts, and I have time to see what I did before doing more.

I work with the shape the tree has. I look at where it is going on its own and help it in that direction by removing what obstructs. I do not impose a template.

I never remove the central leader. This is the most specific change I made and the most useful.

I take out dead wood first, in a separate pass. Thanasis again: clear the dead, then sit down and look, and the tree tells you the rest. Dead wood requires no judgement — it is unambiguous — and once it is gone the living structure is visible and the next decisions get much easier.

I prune in February, after the hardest cold and before growth starts. That part of the conventional advice holds.

Where the books and I part company

Fukuoka argues that a correctly formed tree barely needs pruning at all, and that the natural form of most fruit trees is a central-leader cone.

Two problems with applying that here.

The olive is not a central-leader tree. Left entirely alone it becomes a multi-stemmed shrub. That is its natural form, and it is a poor form for harvesting. His generalisation was drawn from citrus and deciduous fruit, not olives.

And he does not discuss water at all in this context, because in his climate it is not the constraint. Where he grew, a larger canopy means more light and more crop, full stop. Here a larger canopy can mean a tree that does not survive August.

Where he is right, and I follow him without reservation, is on young trees. Ten minutes a year on a three-year-old tree saves hours on a twenty-year-old one. Every tree I have planted since 2019 gets shaped early, with small cuts, so that it carries a framework that will serve it for decades.

What I keep from this

The question is not what shape to cut, but how much canopy this specific soil can water in August
Shallow ground over rock takes more off; deeper pockets take less
Never remove the central leader on an old olive, whatever the diagrams say
Dead wood first, in its own pass, before any decision that needs judgement
Restoration of a neglected tree takes three seasons, not one
Early formation on young trees is the highest-return work there is

Questions people ask

How much can I safely remove in one year? I work in small annual increments now rather than a percentage I could name. What I can tell you is what too much looks like: half the canopy in one winter produced two poor years and a decade of water sprouts. If you have inherited neglected trees, spread the work over three seasons.

Should I open the centre of the tree? Not on old olives on shallow soil, in my experience. Thinning to let some light through is one thing. Removing the central axis is another, and it forces the tree to rebuild from the sides with growth that does not fruit. I did it once and would not again.

Does pruning really help with drought? It reduces the leaf area the tree has to supply with water through the dry months. Whether that shows up as a measurable yield difference I cannot tell you, because I have never run a controlled comparison. What I can say is that the trees I pruned hardest on the shallowest ground came through 2023 in better condition than the ones I left full.

When is the right time? February here — after the coldest weather, before growth starts. Later than that and you are removing growth the tree has already spent energy on.

Dry Farming Vegetables Without Irrigation — the same logic of matching demand to available water, applied to a garden bed
Rainwater Harvesting with Swales and Berms — earthworks in autumn, pruning in February; the two work together

Before you go

I send one letter a month from this hillside — what was tried, what failed, and what the season is doing. No schedules, no promises about yields.

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