Decandling Japanese black pine
Decandling Japanese black pine
I’ve received a lot of questions about decandling since I started writing about it. The basic idea is simple – we decandle pines to replace vigorous spring growth with less vigorous summer growth. There are, however, a number of variables to consider, from timing to needle plucking to after care. The best way to navigate these details is with an experienced teacher. If a good teacher isn’t available, I recommend experimenting – preferably with a tree you consider appropriate for experimentation. (For details about some of the variables to consider when decandling, see “Decandling secrets revealed!“)
The first time I decandled a pine on my own, I had an idea of when and what to cut, but was less clear about how the new growth would turn out. I watched the summer shoots develop very closely that year and ended up learning a lot. I’ve still a lot more to learn. Here’s what the process looked like on one of my more developed – though still young – pines this year.
Japanese black pine – June 2011
Vigorous spring shoot
Spring shoot removed: note that I left a tiny bit of the new shoot – this is where the summer shoots will emerge
Needles thinned
Five needles and a short stub remain
After decandling and needle thinning
The tree is more than a bit straggly at this stage. As the summer buds have begun to appear, I have to wait until fall before I can wire the tree. What does a recently decandled pine look like after a great wiring job? I recommend Peter Tea’s recent photographs of a 100-150 year old pine for an answer. See his Aichien Journal for the story.
Pine decandling
The progress continues on a Japanese black pine I’ve been working on since digging the tree from Lone Pine Gardens some years back. This summer’s work consisted of decandling, thinning a few needles, and reducing the two temporary branches at the top of the tree.
Japanese black pine, approximately 18yrs old – before decandling
After decandling and cutback
The straggly branch at the top left is keeping the trunk alive until a couple of grafts take. I don’t need much growth here, but I want to keep the sap flowing past the grafts. The straggly branch on the right is part of the new apex. I’m letting it grow until the apex is closer in size to the trunk. Once enough grafts take and the apex has reached adequate size, I can remove these branches and actually get an idea of what the tree will look like as bonsai.
Korean hornbeam – summer work
Korean hornbeam can grow dense with little effort. To encourage interior shoots, I need to thin the foliage. I do this by cutting new shoots back to 2-4 leaves and completely removing extraneous shoots from overly dense areas.
Korean hornbeam – July, 2011
After removing the unnecessary leaves, I decided to lower a few of the branches. I remembered that the branches on the right side of the tree pointed upward a bit more than the branches on the left. You can see this more clearly without the leaves.
January, 2011 – note upward pointing branches on the right
To make these branches better match the angles of the other branches, I used several guy wires. There are a number of ways to set up guy wires. For this tree, I stuck to a simple set-up. First step – cutting two short lengths of aquarium tubing.
Aquarium tubing
To create an opening for the wire, I cut a slot in one of the tubes by bending it and taking a small slice from the top.
Creating an opening for the wire
This will be used for the top branch – the one to be lowered. I slip the bottom section of tubing into place as is.
Guy wire with tubing
After slipping the first section of tubing onto the wire, I place the tubing below the anchor branch and feed the ends of the wire through the openings in the tubing with the slot. I decided against shooting the set-up in place as there were too many branches in the tree’s interior to tell how things are connected. Here’s the basic set-up.
Guy wire set-up
After wrapping the wire with tubing around the anchor branch and the branch to be lowered, I twist the wire with my fingers to hold it in place. I then lower the branch with one hand, and use pliers to take up the slack in the wire with the other.
Guy wire detail
Hornbeam – after thinning and adding guy wires
Why not simply wire the branches that need to be lowered? One thin guy wire does the same work as a very heavy wire wrapped around the branch. The process is simple and uses less total wire.
Why use plastic tubing? The tubing slows the rate at which the wire cuts into the bark and it protects the bark from injury and discoloration.
I don’t know if the branches will set before the leaves fall off this autumn. If not, I’ll leave them in place – or remove and replace them – when I work on the tree this winter.
Refining cork bark black pine – decandling
Refining cork bark black pine – decandling
Decandling my cork bark black pine was a straightforward process this year. I removed the spring growth and thinned unnecessary needles. I did not decandle weak shoots or shoots that grew in areas I’m trying to develop – mostly the lower branches on the right side. Here is the tree before decandling.
Cork bark Japanese black pine – June 2011
Most branches produce a single new shoot – strong areas produce two or more new shoots.
Two new shoots – this branch is strong
Main shoot removed – one shoot remains
When two or more shoots appear on a single branch, I remove all new shoots to prevent the branch from becoming even stronger. These branches usually have a main shoot that grows upward and one or more side shoots that grow at angles. I cut all shoots perpendicular to the direction in which they grow. Cutting two or more shoots at the same time produces uneven cuts that can lead to uneven growth.
The weaker shoot grows at an angle
Both shoots removed – both cuts square
As I worked, I found a needle that was green toward the base and brown toward the tip. I likely broke it when I wired the tree in April. My goal is to break as few needles as possible when I work on pines. Lots of broken needles is a common sign of careless work.
Oh my, a broken needle!
After removing the new shoots, I thinned unnecessary needles. This allows more light to reach the lower branches and helps balance vigor. I leave more needles on weak branches and fewer needles on stronger branches.
Shoot after decandling – plenty of needles
Branch thinned to five pairs of needles
When I’d finished this work, I noticed that the tree looked different than it did last year – a good sign. If all goes well, I’ll have the silhouette I’m trying to develop in a few more years.
Decandling and needle thinning complete
Part of the improvement is due to improved branch structure. You can get an idea of what the branches look like below.
First branch on the left
Each large branch is comprised of a number of smaller branches. The subtle differences between these branches provides depth and interest.
One of the branches that comprises the large first branch
For comparison’s sake, see the tree when last decandled one year ago: “Decandling cork bark Japanese black pine“
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