Garden School:

Garden School:
Teaching this week: Nothing: my Trainee is on holiday!

Monday, 21 August 2017

Salix Kilmarnock: How to recapture a runaway

Willow just loves to grow.. and sometimes, they can outgrow themselves.

I was recently sent a picture of a Salix Kilmarnock which was desperately in need of a haircut, as the branches were so long that they were lying along the ground.

Here he is: looks a bit like an armadillo, escaping into the shrubbery!

To remind you, this is a grafted tree: the nursery take some "weeping" willow branches and graft them on to a short upright trunk of a different, non-weeping willow.

It is usually a weeping form of Salix caprea (Goat or Pussy Willow) at the top, by the way, and this is quite different from the proper Weeping Willow - Salix babylonica - which is familiar to us all from riverside walks and willow pattern plates.

They can be made at almost any height - and they never get any taller, because it is not the trunk which is growing, it's the weeping branches which grow, and this photo is a perfect illustration of this phenomenon: the tree is four years, the trunk is still only about, what 3' tall, but the branches are now twice as long, and have hit the ground, and are now having to lie down, instead of swinging freely.

Is this a problem? No, not really, but it's not a good idea to leave them this long, as they prevent air and light reaching the trunk, which might lead to disease, and will certainly lead to the owner being  unable to see what weeds are lurking underneath there.

The thing to avoid here is going round cutting every single branch an inch above ground level - what you might call the "pudding basin" haircut, as that will look awful.

Instead, aim to end up with each branch at a slightly different height above the ground, so that they all swing clear, but are not all the same length. And the real trick is to not have any cut ends at ground level, which requires a bit of skill - we'll come back to that in a minute.

So,  how do you catch this runaway tree? Firstly go round it right now at ground level with the secateurs, and cut off everything that is touching the ground:  cut each of those branches just an inch or two above the ground, to get rid of the weight

Once that's done, get on hands and knees and duck inside the canopy, which I imagine will feel like a small dark cave... look up inside, and see if there are a mass of dead brown branches with no leaves on them. If so, carefully cut them off, as high up as you can, inside the "cave". Dead branches are no use to anyone, and harbour fungal diseases. Clear them away, along with any weeds and dead stuff on the ground at the base of the trunk.

Tip: the first time you do this, choose what looks like a dead branch but before you cut it, circle it with finger and thumb: then slowly run your hand downwards until you get to the very end of it, to make sure there is no live growth further down. No live growth: cut it off, as high up as you can.

Now, crawl outside, stand up, and take a look at it - does it still look very dense? Duck back inside, and see if you can thin out the canopy by removing a few of the inner branches right up at the top, inside. (It's a bit hard to describe this!) If you are nervous about doing this, start by taking out one from each quarter, ie just four branches. Nothing too drastic.  Choose a branch, trace it back to the centre, then once again circle it with finger and thumb,  run your hand slowly down it, pulling in all the side shoots on that one branch. If you gently pull them towards you (while you are crouched, sat, or kneeling inside the cave), you can see what would happen if you were to remove that one branch, before you actually cut it: if it leaves a gigantic slash in the canopy, then don't cut it, choose another one.

Now we move on to the advanced work, and this next part also applies if there are only a few big branches, and you don't feel brave enough to chop any of them off in case they leave a big hole. Instead you can thin out the growth by a technique called "undercutting".

As always, it would be much easier to demonstrate this than to describe it (memo to self: must get a GoPro headcam some time) but I'll try.

Let's imagine that your weeping Kilmarnock tree has been cut in half, right through the middle and has turned into a cartoon on the way.

This is what it might look like: central single trunk, tuft of growth at the top (I didn't draw in all of the branches) and each branch curves out and down from the top.

You will see, on your tree, that each main branch has side shoots growing from it, and because it is a weeping form of willow, they all ("mostly") grow out and down. This means that if you take the tip of one branch, where it touches the ground, and trace it back up, you will find that it is actually not one branch running all the way to the top, but is a sort of compound branch, with side shoots springing outwards from it.

Undercutting means to cut out the inner, lower, section, leaving a usually thinner, lighter shoot. As per the diagram.

You can see that if you cut it there, underneath where the side shoot springs out, you have shortened it, but you have retained the natural look. If you repeat this a couple of times up the same branch, as per this cartoony sketch, you can see that you have take out two branches from the "inside" but have left the growth on the "outside".

Do it right, and from outside it doesn't look very different, but you will have removed up to half of the weight of the branches, allowing what remains to swing freely and lightly: plenty of air can circulate, and it does not look as though it's been hacked with the kitchen scissors.

Best of all, by doing so, you should have removed several of the overlong shoots which were cut off first of all - so instead of having a bunch of chopped ends all at roughly the same length, you should now have mostly non-cut ends, all at different lengths, giving a much more natural look.

That is the technique of undercutting: you cut away the material that is "under" the outer layer of branches.

The final job is to check around the base of the trunk - hopefully you can now see it, and get to it! - to see if it is putting out any shoots: any such shoots must be removed immediately, as they are not "weeping" growth but are from the original (ordinary) willow trunk, and if you leave them, they will quickly grow straight  up, through the canopy, out into the light, and will completely ruin your Kilmarnock.

You can easily identify them because they will be growing from ground level or just above it, and they will be dead straight and heading upwards. If they are tiny little sprouts, rub them off. If they are just a couple of inches big, rip them off. Go on, it won't hurt the tree. If they are bigger than a couple of inches then you will have to cut them off with the secateurs, but be sure to cut them off as close to the trunk as you can, and be aware that by cutting them, they will probably grow back, so in a month or so you will have to check again and rub off any new growth. Literally, rub it off with your thumb while it is tiny.

If  you find new shoots springing up from the ground around the base of the tree, you will need to remove these ones as well: gently scrape away the soil until you can see where they are growing from, and pull them off: as above, if you can't pull them off (either because they are too big, too tough, or are sprouting from too far underground) then just cut them, but be aware that you will have to keep rechecking every couple of months, because Cuts Will Re-grow. 

There you go, that's How To Do It: firstly do a rough cut to get rid of all the trailing branches, cutting them just an inch or so above the point where they touch the ground.

Check inside, and remove any dead branches.

Thin out the canopy - just a little, if you are nervous or haven't done this before.

Undercut the longest branches to restore a more natural "hem" to the tree - aim for a light, airy waterfall.

Check the base of the trunk for shoots and remove any that you find.

Clear away the mess, take a photo, job done!

1 comment:

  1. I only bought this this year (for the bees) but will keep your post bookmarked for future reference. I have since discovered that I should have bought the female (Weeping Sally) in preference but haven't had any joy finding a supplier.

