Before we get down to the HOW TO – let’s start with the WHY? WHY prune your citrus trees? If you follow the 4 D’s rule you won’t go far wrong: DEAD, DISEASED, DROOPING and TOO DAMNED TALL.
Most people feel bamboozled at the thought of having to prune any tree – let alone citrus. Follow the 4 D’s and the tips below and everything will be fine. Trust me I’m and arborist!
It’s autumn, here in the subtropics, and citrus season is upon us with bumper crops of oranges, grapefruit, lemons and mandarins ripening on the trees and weighing down the branches. I have often pondered how clever nature is to provide us with this healthy bounty just when we are coming into winter and need all the help we can get to fight off coughs and colds. The word serendipitous comes to mind?
We are also in the middle of the global pandemic, covid-19, and I have read, in more than one article from more than one country, that Vitamin C is being prescribed to those who have tested positive to the virus, but not sick enough to be hospitalised, as a simple and age old remedy of boosting the immune system.
Over the past few months, I have certainly been grateful for the huge crop of limes that I have picked from my one small tree – I’d estimate at least 40 kilos and I thought that it was almost done, until I went to prune it and picked another bucketful. Limes are the first citrus to fruit in the season – first in a long procession that will last until the end of winter. SO NOW IS THE TIME TO PRUNE THIS TREE.
RULE 1: Prune citrus when they have finished fruiting and before they start flowering and putting on spring growth. When you actually do this will depend on what type of citrus and the variety you have – some are early fruiters, some are late.
You may lose a few small unripened fruit but, believe me, you will reap the benefits come next fruiting season. Be brave, have a go. Just follow the 4 D’s at the top of the page as a guide but the most important is the last – TOO DAMN TALL.
RULE 2: The main reason to prune is to reduce the height. 2-3 metres is ideal. If the tree has become so tall that you can’t pick the fruit – then IT NEEDS PRUNING. This is what I was doing to my lime tree. We also want to increase blossom quality and therefore fruit size and yield. Giving it a light haircut does this.
RULE 3: Get the right tools for the job. You don’t need many, so buy good ones and look after them – it will make the job a lot easier and quicker. This is what you will need from pruning a citrus tree. You will also need good gloves, long sleeves, a hat and eye protection – CITRUS ARE THORNY.
- A pair of telescopic, heavy duty loppers. A decent cutting blade will mean that you will easily be able to sharpen them.
- A hand pruning saw. You can’t sharpen these so its not worth paying too much, but really cheap ones will just not do the job – they will bend and stick as you are sawing.
- A pair of hedging shears. Again, good quality so that you can sharpen them over and over again.
- File for sharpening.
Pruning tools: From left to right Hedging shears. Telescopic heavy duty loppers. Hand pruning saw. File – this is actually called a bastard file – it has a criss-cross pattern for removing fine amounts of material from a hard metal edge, like those on the shears and loppers. Diamond sharpener – for honing the edge after you have used the file – also good for secateurs. This is too fine to do the whole job on the shears and loppers.
RULE 4: Start to prune your citrus trees from DAY ONE. It is very hard to make a ‘silk purse out of a sow’s ear’ – i.e. it is very hard to turn a ten year old unpruned, unloved tree into something beautiful, healthy and productive (a bit like people really!)
- Following the 4 D’s on a friend’s lime tree. Remove DEAD or DAMAGED branches, branches growing inwards and very low branches to improve air circulation. LIFT THE SKIRT. After pruning, the lower edge of the canopy should be 60 – 90 cm clear off the ground otherwise branches and fruit will drag
- This is the ideal height for a citrus tree. No more than 2-3 metres
- Note the cracked and dry soil in the first picture.
- Note the mulch out to the dripline in the AFTER picture. The tree was also given a complete fertilizer.
- You might be wondering what the hedging shears are for? To go over the whole tree and give it a light haircut when you have finished the rest – you do not have to be too fussy. I got this tip from an episode of ABC Gardening Australia, where this was just about the only tool a commercial citrus grower used. Because he kept his trees small, he could just go over them once a year with the shears. This encourages sideways shoots and therefore more flowers and fruit.
RULE 5: Don’t overdo it! You want to leave the tree with a good covering of foliage so that the trunk does not get sunburnt and you get some fruit next season. It seems to be fatal, with some folk, to hand them a pruning tool – they get really carried away. I can’t tell you how many times I have delegated a pruning job to someone, only to return later to a skeletonized stump!! In the AFTER photo above, you wouldn’t really know that the tree had just been worked on for an hour? That’s the way it should be.
A NOTE ABOUT CITRUS GRAFTING: All citrus that you buy have been grafted. This means that two different species of citrus have been ‘cleft’ together to make one plant. Generally the ‘rootstock’ is Citrus trifoliata (meaning-three-leaves) and is used because it is resistant to a soil borne disease called phytophthora which, in the past just about wiped out the world-wide citrus industry. The ‘scion’ or main plant on the top is the desirable species, be it Seville orange, Eureka lemon, Tahitian lime etc.
If you look carefully at a citrus plant you can always see where it has been grafted – it’s where the ‘dog-leg’ is!
RULE 6: Remove all growth shooting from below the graft.
- The photo above shows unwanted shoots of trifoliata which grew below the graft of my lemon tree- TAKE THEM OFF!
- Most citrus will throw out a few of these unwanted shoots. A regular part of pruning maintenance is to remove shoots of trifoliata from below the graft as soon as possible, as they steal vigour from the tree and, if left too long, and can leave large wounds for disease to enter when they are cut.
- They are viciously thorny so be wary handling them!
Rule 6: Wasp Gall Damage – a common pest of citrus
- You may notice these swollen lumps on citrus branches – make sure you prune these and destroy them. This is the damage that the burrowing wasp gall makes – if left, they will weaken the tree and eventually destroy it.
- A healthy tree that is receiving regular feeding, mulching and water will be more resistant to pests and diseases than one constantly under stress.
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