The other day I had a good time giving a talk about growing citrus to the Lake San Marcos Garden Club, and a couple of people asked me about pruning. My impression is that most of us think that, as a general rule, all fruit trees need to be pruned. It’s simply not true, especially regarding citrus. In contrast to this mistaken notion I’d say that, as a general rule, citrus should not be pruned. I can think of only a couple of exceptions to this rule.
In my yard I grow eight citrus trees, and out of those eight I only ever touch two with my pruners, each for a different reason.
PRUNE TO KEEP A CITRUS TREE SMALL
I give our Bearss lime tree haircuts because I want it to stay small, to about the height of my three year-old son. It already produces more limes than we use at that diminutive size. Once a year I prune it by just trimming off every branch that is taller than I want, or by handing Cass the pruners.
PRUNE TO SHAPE A CITRUS TREE
I also prune our large Valencia orange tree. It’s 25 feet tall, and I’ve never tried to trim the top. Rather, I prune the sides and interior to create an umbrella shape. I keep its skirt a few feet off the ground and then I keep the inside pruned high enough that we can walk around under it so that it feels like an outdoor living room. I prune up a couple of spots on its canopy edge to make doorways for entrance. Shaping this citrus tree in this way makes it a very comfortable spot to sit in the shade on a summer day.
Keeping a tree small like my lime and shaping a tree like my Valencia are the only two good reasons I can think of for pruning citrus. There are plenty of bad reasons though.
DON’T LACE A CITRUS TREE
The worst reason, or way, to prune a citrus tree that I’ve encountered is opening up the tree’s canopy so the interior gets sunlight. That can be a good idea for some other types of fruit trees, like plums and peaches. It’s definitely not advisable for citrus, however.
Why not? I once did a home consultation at a multi-million dollar residence in Rancho Santa Fe where the owners had put in an orchard of a few dozen fruit trees and then their hired gardener had pruned all of the citrus trees just like the peaches and plums. The foliage had been thinned, entire branches had been cut out, the canopies had a skeletal look, and the effect was that you could see lots of light going through the trees and hitting the interior branches.
Why are our citrus trees dying? the owner asked me. All of those interior branches now exposed to the sun were cracking and blackened from sunburn. Yes indeed, trees get sunburned.
If you want to keep a citrus tree small or shape it, then trim the outside like you would trim a hedge. Don’t cut out entire branches and expose interior parts of the tree that are used to being shaded. Have a look at this video showing how citrus farmers mechanically prune their trees. This farm is in Spain, but the same technique is used here in Southern California, and the world over.
A citrus expert once told me that if a citrus tree is in prime health, then if you look at its canopy you won’t be able to see any light or sky through it. It should be a dense green globe.
A couple of other no-good reasons to prune citrus include cutting out dead or crossing branches. That’s just a big old waste of your time. Do it if you have nothing better to do, but your citrus tree couldn’t care less if some of its branches are crossing or are dead and hanging. Both are harmless and natural. I don’t cut out any dead or crossing branches on my citrus trees and they’ve never complained about it.
Also, if aphids or leafminers or other insects have damaged the leaves of your citrus tree, don’t waste your time cutting those damaged leaves out. They’re still capable of photosynthesizing and contributing to the growth and fruitfulness of the tree even though they’re not completely healthy. Pruning them out won’t make a significant difference to the insect population in the tree either. Better to adjust your aesthetic sensibility than cut up the tree, in terms of the health of the tree.
Lastly, and here’s a bit of a twist, do pay attention to what’s growing from low down on the trunk of your citrus tree. I don’t think of this as pruning, but it’s really important that if any branch starts growing from below the graft (bud) union of your citrus tree you immediately remove it. If you’re unsure of what I mean by that, then please read my post titled, “Beware of rootstock suckers on citrus.” It might save the life of your tree.
Isn’t it a relief, though, to know that your citrus tree knows how to grow pretty well on its own? That’s why you can find citrus trees thriving even in Southern California yards that have been neglected for years. And that’s why every Southern California yard should have a citrus tree, or eight.
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