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De-candling and Stuff!

Updated: Oct 8, 2020

Now that Summer is in full swing, we’re moving away from the deciduous into the Black/Red Pine work.  During the Summer is the time we start to de-candle the many Black/Red Pines we have here at Aichien.  For new and seasoned Bonsai enthusiast, the concept of de-candling can be or still be confusing and misunderstood.  Black/Red Pines in general are more difficult to work on because of balancing issues and one of the most difficult trees to balance.  In this post, I’m going to talk about the concept of de-candling, when it’s applied, the results and the other details surrounding the concept.  I will also talk a bit about cutting back and thinning of the tree as well.  Of course, I’ll be sharing some pictures of the process.  This is by no means the definitive guide to de-candling which is normally best taught by a trained and skilled instructor besides you, but this will give you an idea of what it’s all about.

What is De-candling, Some Terms and How it Works?

De-candling is the removal of new growth on Black/Red Pines during the Summer.  De-candling is a very stressful process for the tree so be sure to only de-candle trees that healthy and growing well.  Think about it for a second, we’re going to be removing all new growths from the tree.  Most trees don’t like that! :op  It just turns out that Black/Red pines are able to respond to that process and survive.

De-candling can be done on a Black/Red pine for 1 or all 3 of the following reasons:

1. Branch Division – new buds will appear and grow at the base of the cut creating a division in the branch structure.

2. Short internodes and Shorter needles – since the candle is cut in the middle of Summer, the new candles that grow will only have the rest of the Summer and Fall to grow.  The growing season is essitenally cut in half, the new candles will have a shorter season for growing, resulting in shorter internodes and needles.

3. Back-budding – by removing the candles and putting stress on the tree, the tree will produce buds at the cut point and along the branches as well to recover and survive.  On Black/Red pines, branches that are older than 4-5 years old tend not back bud as easily.  If there is bark on the branch, it will almost never bud in that area.

I would add, “balance,” to the list but everything we do in Bonsai revolves around balance so it’s pretty much a give in.  ;o)

Some Terms:

Spring candles – New growth at the start of the Spring season.

Spring needles – Needles that extend from the Spring candle

Summer candles – New candles that grow during the Summer and Fall because of the De-candling process.

Summer needles – Needles that extend from the Summer candle

Internode – section of the candle that has no needles

The Process

Note on Wiring

Assuming that the tree is healthy, wiring can be done on a Black/Red pine after de-candling.  Heavy bending can be done as well but more care has to be taken not to twist branches too much because the cambium layer can separated from the heartwood easily during the growing season.

Wiring can be very stressful to the tree as well.  When an entire tree is wired (strong, medium and weak areas) the tree tends to take the stress well.  If only certain areas are wired, this can cause a lot of imbalance with the tree, especially if the wired areas are weak.  Since weak areas are under a lot of stress whereas the strong areas are not, this could more times than not, cause the weak wired branch to die off.  Trees always want to get bigger and grow stronger.  If the tree finds that the strong areas are growing well and the weak areas are under stress all the time, the tree will cut off flow to the weak areas and dedicate its energy to the strong areas instead.

In this case, the entire tree was de-candled causing stress overall, and the weaker lower branch that was wired was not de-candled so the stress is limited.  By keeping the work (stress) on the tree more balanced, the overall tree will grow more even.

Often times, when working on any tree, there will be a weak branch that I want to positioned in a sunny area.  Mr. Tanaka would tell me that if I only wired that branch, there is a 50/50 chance it will die, whereas the chance of living increases, if the entire tree was wired. Sometimes people will tie a rope to those branches to move them instead to create less stress.

Lets Compromise

De-candling isn’t an all or nothing process.  Depending on the tree and the varying degree of strengths, some areas may be de-candled and other not.

For example, if you’re working on a tree and every branch pad has strong candles (candle on the right of the photo) except for one branch pad that  has weaker  small candles (candle on the left of the photo), what should you do?  In that case, the weak pad should not be de-candled because relative to the rest of the tree, it is very weak.  If the whole tree has medium size candles all over, then it’s safe to de-candle everything.  Of course, there is a point where small candles on the entire tree just means the whole tree is weak and should not be de-candled at all.

Just To Make Things More Complex

De-candling is pretty straight forward right?  Well not exactly.  Remember when I said that Black Pines are one of the most difficult trees to balance?  De-candling can play a huge part in that.  Depending on the individual bonsai professional, different techniques of de-candling can vary greatly.  All of them will have their reasons for their methods and many times the different techniques yield the same results anyways!  Sometimes it just comes down to personal taste and preference.  I’ve even come up with my own preferred way to de-candle as well!

What I’ve shown above about de-candling is the basic concept.  The technique can get more complex from there on.  I’m not going to get into the other different techniques too much but here are some basic information about them:

1. 10-10-10 method – de-candle the weak candles first, 10 days later the medium candles, then 10 days later, the stronger candles.  This method is used with the idea that cutting the weaker areas first, will give the new buds an advantage in time to catch up with the stronger areas before they start to push new growth.

2. 10-10-10 Plus method (I coined that term myself because I don’t know of a name for it) – The technique is the same as 10-10-10 method, except when de-candling the weak candles, the professional will go and pull off the new needles from the new Spring candle in the strong areas as well.  So now you have a tree where the weak candles are cut, the medium candles are intact with needles and the strong candles are intact but with no needles.  10 days later the medium candles are cut and 10 days after that, the strong needle-less candles are cut.  Not so much as a different method as the first, but a modified version.  The idea behind this technique is to greatly reduce the strength of the strong candles.

3. Peg or Neck method – depending on the strength of the candle, part of the candle internode is left and acts a fuse to when the buds at the base of the candle will form.  The stronger the area, the longer the internode (peg/neck) is left on.  The idea behind this method is that the weak areas have no neck and will start to develop buds first, whereas the strong areas that have necks will need to dry up first before it start to produce buds, giving the weaker areas a head start.

4. Needle reduction method – Every candle is de-candle all the way to the base of the candle.  Then based on strength of the area, old needles will be reduced to a certain count.  The strong areas may only have 5 pairs of old needles whereas the weak areas will have 9 pairs of needles.  The idea behind this method is that by reducing or providing food (needles) in an area will weaken or strengthen the new Summer candles to achieve balance.

5. Combination method – methods 3 and 4 are combined, usually because the tree is so imbalanced that one method alone won’t do the job.

So all these methods to achieve pretty much the same desired goal, “BALANCE.”  If bonsai people took that much time to come up with all these techniques this whole balance concept must be important.  ;o)  In the future as I get more photos of the different techniques, I’ll post supplemental information in regards to de-candling and the results


Thinning a tree can be a very complex procedure.  There are so many variables involved in understanding which branch to keep and which branch to cut.  Variables such as branch strength, length, and size are some examples.  Learning to thin a tree or cut back a tree is not something that is easily learned by reading a book or even reading this blog!  Haha!  This skill is learned through deeper understanding of bonsai, experience working on trees that need thinning and is usually best taught by an instructor (Lets be real, skill is usually learned best through an instructor).  So instead of trying to teach the concept of thinning and all its variables, I will provide some examples just so you can get an idea of what it’s all about.

So When Should I De-candle?

Depending on your weather pattern and tree size, de-candling times will vary.

Large trees vs. small trees

Since de-candling allows us to have shorter than normal needle lengths, we can play around with it a bit depending on the tree size.  Large trees should have longer needles and smaller trees should have shorter needles.  This helps in making the tree more proportionate looking.  Since we know that by de-candling we will produce shorter needles, which trees to be de-candle first?  Large or small?  Thinking about it now…

Answer? Large ones first!  Reason is because we need the large trees to have longer needles so we have to give them a longer growing season for the needles to grow, hence, de-candling them earlier in the Summer.  Usually small trees are de-candled towards the end of the de-candling period.

Long vs. Short Summer and Fall

In Japan, De-candling normally starts at the end of June for large trees and ends at the end of July for small trees.  Japan has a fairly long and humid Summer and Fall season.  By December, the new Summer candles will have fully grown with short needles and have hardened off.  In the California Bay Area,where the growing season is longer but less humid, the de-candling process starts at the beginning of June and ends at the beginning of July for small trees.  That gives you an idea of how humid is a big player in how well trees grow.

So thinking about what your weather is like in your area to figure out when you should de-candle your trees.  If you’re not sure, start a little earlier such as the beginning of June or late May and see how the tree responds.  If the Summer candles needles grow too long this year, next year when de-candling adjust your timeframe forward by a week or two.  If the Summer candles and needles are too short, then adjust next year’s timeframe back a week or two.  After two to three seasons of de-candling, you should be able to get a pretty good idea of when is the best time for you.

Is My Tree Ready or Can Handle De-candling?

Now that we have an idea of what de-candling is all about, do we go out and de-candle every Black/Red Pine we see?  I think you know the answer to that by now… ;o)

Since de-candling is stressful to the tree, it’s important to understand that only strong healthy trees that have been more developed should be de-candled.

The biggest reason why weak trees should not be de-candled is because weak trees will not respond to it well.  Instead of producing Summer candles, the tree will either produce only small buds that will sit till next year to grow, or the branches will do nothing and start to die off.  This tree was also repotted this year so it’s already gone through a good amount of stress.

When To Fertilize

Fertilizing is very important when De-candling Black/Red Pines.  Fertilizing should start at the beginning of the Spring season.  We want to feed the tree well to make them nice and strong before we de-candle the tree.  After de-candling, all fertilizers are removed and even the top soil is scrapped off and replaced. Fertilizing should stop for about 4-5 weeks after de-candling, then resumed moderately once the new Summer candles start to grow.  If we started to feed the tree heavy after the 4-5 week break, we run the risk of the new Summer candles growing just as big as the Spring candles, defeating the purpose of de-candling. If we continue feeding heavily right after de-candling, the roots could potentially burn because the tree can’t take that much food anymore and the soil becomes too toxic with nutrients.  This is the same as if we were to dump a bunch of food on the soil after freshly repotting a tree.

Well, that’s about all I have to say about de-candling at this point in time.  I hope that this information gives you more insight to the process and why it’s done.  Black/Red Pines are so fascinating to me because of its beauty and complexity.  Balancing them is like a mystery that needs solving and it turns out that the answers are mysteries in themselves!  I’ve said this before and I still say again today, if a person can balance Black/Red pines, that person can balance any tree.

Thanks for reading!

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