Pruning – one size does not fit all

Even before the internet and televised sport there were armchair experts. When it comes to plants every man with a dog and retired lady who makes tea has a ‘how to’ on pruning; some of these are good, some of these are not that bad but most are just wrong.  In defence of the bad, I suspect the issue is the term; pruning.  Pruning is a catch-all term meaning to trim or cut away dead branches or overgrowth.  Like many things, there isn’t just one sort of pruning, and there the problem may lie – how you prune roses is completely different to how you prune trees, and how you prune a fruit tree for fruit is very different to how you prune a fruit tree for appearance.  You’d never prune a camellia the same way you prune a grapevine and just to confuse things you might prune an orange tree to enable a dove to fly through it [the Asian mystic way] but never do that in New Zealand!  So there is pruning and then there is pruning and then there’s pruning, occasionally the man with his dog is correct and sometimes ladies that make tea know what they are talking about but not always and often not.

It doesn’t actually get any better for those that have undertaken formal training.  There seems to be pruning terms for the sake of having pruning terms. Trees for example can be pruned by crown lifting, crown thinning*, crown cleaning and/or crown reduction.  In reality all pruning results in reducing the crown, so we could call everything a crown reduction, but sometimes the crown is at the bottom of the plant like it is with roses.  And then the placement of pruning cuts; node or internodes… unless you are taking a cutting, you should never cut at an internode (but if you are taking cuttings you’re not pruning, so you’d know that).  Back to trees, how do you prune a tree so its first permanent branch is 3m above the ground if the tree is only 2m tall?  What is pinching?  And of course, pruning principles go out the window when you hedge, which is probably why most hedging is done badly.  Trying to understand pruning almost makes you want some tea and take your dog for a walk…  

So how to prune? 

In the knowledge that one size does not fit all, let’s talk to the big picture 

1) Plants grow, which should be obvious but in terms of pruning always think in terms of where will the new growth be.  Shape your plants with the new growth not the pruning cuts and if there isn’t growth where you want it, leave something to grow into the gap.

2) Focus on formative pruning when the plant is small – get the structure right at the start (remove inward growing and/or crossing branches) then future events will become quick and easy

3) Always prune back to live growth, be it a bud or a branch.  And make the cut as close as practicable to the live growth (but not so close that you damage it)

4) All pruning wounds.  Even a correct pruning cut makes a wound, so keep the size and number of your wounds to an absolute minimum – if you don’t know for sure where to make a final cut, then cut the branch at 90 degrees (it’s not going to be the correct cut, but it will create the smallest wound).

5) Don’t make angled cuts so the water can run off, wood is waterproof – we age wine in wooden barrels and wooden ships sail the oceans.  Angled cuts make larger wounds and require more effort – smaller cuts are easier and better for the plant

6) Don’t apply pruning paste, paint or grease to your pruning cuts – it will do more harm than good and it will do no good at all (maybe in an orchard situation it might still be acceptable, but I don’t even think they do it any more)

7) Good pruning will result in the plant looking smaller but otherwise fine – if it is obvious that the plant has been cut, if there are stubs and odd branches pointing this way and that, that’s not pruning, that’s poor work

8) If you are using a handsaw then the branch you are removing will be big enough to tear the bark if it falls, so remove the branch in two pieces, 1) 100 to 200mm past where your final cut will be then 2) come back to as close as practical to the live growth and make your final cut (the smallest wound you can)

9) If you are using a chainsaw to remove a branch and you don’t know for sure where to make a final pruning cut then stop it, put the saw down and walk away – you’ll only damage the tree and you’ll probably hurt yourself in the process.

10) Remember trees don’t heal, they seal.  Remember this, because the mistakes you make will be sealed into the tree for the rest of the life of the tree.  Don’t let your children and/or grandchildren see how useless you were… if you don’t know what you are doing – don’t do it!

And hedging…. 

11) When it comes to trimming a hedge, start at the widest point and trim it back as far as you can (but to live growth), then blend the rest of the hedge in to meet that point.  The bottom/base of the hedge should be slightly wider than the top (this is to prevent the top from shading the bottom so an even growing face is made)

Pruning shouldn’t be complicated, if you don’t know what you are doing but have to do it then make your cuts as small as you can – do the least damage.  If in doubt, get someone in. Don’t worry about timing, do it when you can, if you can and clean up the mess (note; it will take about three times as long to clean up the mess as it takes to create the mess, and twice as long again if you leave the mess and come back to it at a later date).

There are several good resources out there, but be wary of opinion and people that make definitive statements; there is pruning and then there is pruning and then there’s pruning.  And lastly keep your hands away from the sharp bits – handsaws injuries account for more lost time than chainsaw injuries in the arboricultural world; keep your hands away from the sharp bits, cut away from your body and always use a chainsaw with two hands.

For tree pruning and general tree care, check out Trees are Good:

* never undertake crown thinning – its old school, its wrong – don’t do it and if you do, stop it!

• Written for the NZ Landscaper Magazine