(GENTLE MUSIC)
SOPHIE: In winter, when your deciduous trees are dormant
and bare of all leaves,
it's a pretty unmistakable sign
that it's time to prune.
And, helpfully, when the trees ARE bare,
it's easy to get a good look at the structure,
which helps make decisions about how to shape your canopy.
On this show, we often talk about pruning fruit trees.
Here in the orchard, my aim is to keep the canopy low
so that it's easy to pick the fruit.
And I often will take out the central leader to create a bowl shape
so there's lots of light and air movement.
When it comes to pruning deciduous ornamental trees,
it's an entirely different strategy.
Usually we want the canopy to be high
so that we can walk or sit beneath it.
Today, I'm going to prune
some trident maple trees in my car park area
'cause I want to lift the canopy so we can park cars under their shade.
But first, I'm going to show you why.
This ornamental snow pear, Paris nivalis,
is an example of an unpruned tree.
It's also an example of what not to do.
Now, I planted it a couple of years ago
and I should have lifted the canopy.
But I didn't.
So, as you can see, it's branched low down and put a lot of growth on.
Now, I do need to lift the canopy.
And when I cut those branches off, all that growth is wasted.
I would have been better to raise the canopy when it was young
and put more energy into developing a lovely big tree.
Another example in my garden is this tree
that's branching too low to walk under comfortably.
It's a Pyrus 'Winter Glow'
and it probably could have used a prune
in its early years too.
Next in the procession of my tree pruning failures
is this one.
It's another ornamental pear, Pyrus 'Edgewood'.
Now, a few years ago,
I did lift the canopy to 1.4 metres
but that wasn't enough.
I should have taken it up above head height, say, to two metres,
so there was more space to walk around underneath.
It's time to get to the trees that need shaping today.
I planted these five trident maples two years ago
when they were already relatively tall.
Now they're two or three metres, which is a perfect size for pruning -
not too old, not too young.
It is possible to lift the canopy of a tree too early.
When a tree is young and it's in a harsh spot like this,
the lower limbs actually protect the trunk from sunburn.
When the bark gets damaged by sunburn,
it can be an injury that never heals
and the tree can even die.
But these trees are now large enough
that the rest of the canopy will prevent that.
They will eventually grow to be about six metres tall
and will take up a lot of space.
I want the area underneath to be usable,
so I'm going to remove these lower limbs.
Cut as close as you can to the collar.
That's the shoulder between the branch and the trunk.
If you cut in the right spot, the cut will heal over
and you won't see a scar down the track.
But if you leave a short stubby bit,
that can actually die back and cause disease.
Some branches can be cut with secateurs or loppers,
but thicker ones will need a pruning saw.
The car park area is a pretty harsh spot for these maples.
The surface is crushed limestone.
It faces north and it's very hot in summer.
Because they're so exposed here,
I'm gonna do this job over two years.
I'll cut the lower branches up to about a metre high today
and then go up to two metres high next winter.
If these trees were growing in a more sheltered position,
then I'd just do the lot.
To avoid stressing the trees, the general rule
is never to remove more than a third of the tree at once.
These are looking good. I'm not gonna take any more off today.
In spring, the tree's gonna direct its stored energy up
into growth in the higher part of the canopy
and eventually we'll have this beautifully shaded area
where we'll be able to walk around underneath and park cars.
We prune deciduous trees in different ways for different reasons.
So before you get out your secateurs,
think about what you need from your tree and do some research.