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Needle Therapy

Some have found fault with Japanese black pine as bonsai material because they typically have needles longer than ideal for smaller trees. Until recently, the technique to shorten needles was to withhold water and fertilizer in spring, until the needles had hardened off. This technique weakened the tree, causing branches to become leggy and thick, and buds did not break back closer to the trunk. Japanese black pine bonsai seemed to be in a steady state of decline from their initial styling, all in pursuit of short needles.

Several decades ago, the preferred technique included grouping the candles into four categories: strong, medium, weak, and very weak. The very weak candles were allowed to grow. The weak candles were cut first, followed by the medium about a week to ten days later. The strong candles were cut last, again about a week to ten days later. This has caused a great deal of confusion among enthusiasts. But things have improved in the last 30 years.

Modern candling technique has come to us partly by happy circumstance, and partly by careful scientific observation and experimentation. Here’s the story I received from Boon Manakitivipart:

Today’s decandling technique was found accidentally, about 40-50 years ago. One spring day in Aichi Prefecture, Saichi Suzuki noticed that several of his Japanese black pines had been attacked by insects (probably caterpillars).

On one of the trees, all the new spring candles were completely gone. Since the old needles were still there, he continued to water the tree. After a few weeks, he saw new buds starting to come out. There were multiple buds at the base of the eaten candles. As the season progressed, the new candles opened up and the needles were short.

A year after this incident, he started experimenting on smaller trees. He cut the candles at different times – and at different lengths. His records showed that the best time to cut the candles was around the middle of June to mid July. If it was done earlier, the needles became too long. And after mid-August, new buds would form, but would not open up until next spring.

This is how the Master of my Master’s father became the discoverer of the Japanese black pine decandling technique.

So this was the beginning of what has become a modern, scientific technique to produce needles of whatever size one needs on a Japanese black pine bonsai. However, needle size is only the last in a line of desirable outcomes from candling black pines. The new techniques not only eliminate the long “necks” on new growth, produce short internodes, and increase ramification through forcing a second season’s growth, they also induce back budding at a much accelerated rate. This produces results much more quickly than the older techniques and provides trees with a great deal more foliage to work with, giving more options to the stylist. All this is accomplished without significantly weakening the tree.

For energy balancing techniques to work, it should go without saying that the tree must be healthy. The more vigor the tree has, the more predictable your results. Removing candles and needles selectively weakens your tree, so doing these things on a weak or sick tree can be fatally damaging to it.

The plan for making this system work is to feed your JBP strongly in the spring, from the first bud movement until candling. Encourage the candles to grow. If the tree is very unbalanced, and you have a long candle or two, you can break them in half, but you do not need to do so. Better to let the candles grow unhindered, regardless of how long they become. In just a few seasons they will be under control.

Candling is done by watching the calendar, not the tree. Regardless of how long the candles get, and how far the needles open or harden off, wait until the proper time to candle your tree. So what’s the proper timing for candling JBP? In Kansas it’s the third week of June to the first week of July, depending on what you want for the tree. We have a long, late, hot season extending temperatures into the 30’s C or 90’s F through the month of September. If you live in warmer climes, candle later. If your growing season is shorter, candle earlier. The longer the remaining growing season, the longer your next crop of needles will be.

This knowledge allows us to deduce another technique. The shohin below has needles approximately 10 mm long. This tree is the last one candled every year. This technique will allow you to decide (through trial and error) when to cut each tree’s candles to get the needle length you wish. One caveat to this technique is the assumption of no unusual summer weather. A large pine candled in June may develop needles far too short if the summer suddenly turns cool and wet.

Cutting the candles
Your shears must be as sharp as humanly possible so as not to damage delicate tissue. On older, more valuable trees, you may want to clean your blades and hone them more than once while working.

The technique is quite simple but must be followed very carefully. Always cut straight across the neck of the candle. Cutting at an angle allows one side of the neck to be stronger than the other, contributing to a disorganized, unbalanced growth. Take care not to cut other needles, so use your hands to support the shoot and approach the candle with the shears closed; only opening them as you can touch the candle to be cut. Make a single clean cut.

In recent years, the best practice has been to group the candles into three or four groups, depending on the strength of the candles.  For instance, in the following photo, the areas circled in red are strongest, the yellow are not as strong.

This all sounds quite complicated, and it is to some extent. Recently, however, it has been simplified tremendously. We are still going to leave alone the smallest, weakest candles. Everything else goes on the same day. This is how it looks:

Figure 1. The new candle starts to grow in spring. This photo shows the candles just opening up.Figure 2. Wait until the new needles grow and open up. This is not too far developed before cutting the candles.

The circled area, the “neck” of the new candle, is bare. Naturally shorter necks are desirable for bonsai stock, as they tend to grow more compactly. However, these techniques provide a short neck where Mother Nature is deficient. Where there are no needles, there are no buds. Adventitious buds are in the bark itself, and remain dormant if nothing disturbs them. However, each needle pair holds a bud. If the needle cluster has three needles, its bud will be very strong and will grow by itself.

Figure 3. Cut the new candle off completely.

Notice that I am cutting this candle at the base of the needles, rather than at the base of the neck. This candle is quite strong, so leaving as much as 10 mm (for the strongest candles) will tend to hold back this shoot just a bit. For weaker candles, leave a shorter stub. Follow this through for all candles except the weakest, and any you need to allow extension for styling purposes. Stubs can be removed in the autumn during needle plucking or in spring during wiring time.

Figure 4. Cut perpendicular to growth

Following candling, we are going to make our energy management more intense by plucking needles. Instead of waiting until autumn, we will remove needles from throughout the tree, leaving as few as five pairs of needles in the strongest bits of the tree (where we left long necks) and as many as ten pairs in the weakest bits. Foliage draws energy, which will encourage the new buds to develop. For this reason we leave more foliage with weaker buds, and vice versa. For areas in which more branches are needed, you can leave extra needles. There will be a chance to get new needle-buds to come out.

Figure 5. This will tend to make your tree, especially a young tree in training, look a bit like a plucked chicken.

Don’t worry about this, when the new buds form and open into needles, you will be amazed at how quickly the tree has filled out and developed!

Following candling, remove the fertilizer from your tree. Once the new needles have set, replace it. This will keep the new growth from getting too long and the needles from being out of proportion.

Fig. 6 In about ten days, you will see many new buds forming at the base of the necks you cut off. Contrary to previously taught techniques, DO NOT rub any of these off! Leave all buds to extend, open, and set needles. This is another new aspect of this technique. Since the stronger candles will produce more buds, removing competition only strengthens the remaining ones on that strong candle. This is exactly opposite to the result we wish. Let them compete, and in the autumn select the pair you want.

When autumn has arrived, and you are ready to think about putting the tree in its winter rest, remove all of the remaining needles from this spring (the five to ten pairs you left on the tree at candling). At this time select the shoots to remain. You have created two seasons’ growth in one summer.

Which shoots should I leave? For years we have been taught, “get rid of any upward or downward shoots.” The problem with that teaching, if followed rigidly, is that your branches fan out without any depth to them. Some side to side and upward-downward buds should remain. The lower one will become your branch extension, and the upper will become an upper branch for depth.  This will make your trees far more natural in appearance.

At this time, you will also wish to pluck needles again if the tree is not going to be shown. To bring the tree further into balance, we can once again pull this year’s needles to leave as few as five pairs at the top of the tree and up to ten pairs at the bottom. For a tree that is mature and well balanced, you may adjust these numbers to keep the tree in good balance.

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