A bonsai truism is that in fall we get to clean up the mess we initiated in the spring. And for pines, this mess is most apparent for the multiple flush species, like Japanese Black Pine.
Black Pine will regrow from a technique known as decandling, when we cut off the spring shoots. The pine sends out 1 or more shoots over the summer from the cut site. How to choose which shoots to leave and which needles to pull are the cornerstones of fall multiple flush pine maintenance.
A typical Japanese Black Pine branch in fall, decandled in the spring. A large pot and sufficient fertilizer has given 2” needles on the summer regrowth. Very short needles are not recommended year after year as they can weaken the plant. The goal of decandling is primarily a short shoot and bud potential all the way down that shoot, but we also get nice short needles. At least, shorter than the 5” needles of a naturally growing plant.
Same branch looking down into it.
Let’s take one set of shoots to prepare for next spring. This one has 3 shoots that grew since this year’s spring decandling, 2 stronger ones and 1 smaller one.
Looking down on the same group of shoots.
Cutting the smallest shoot of the 3 shoots. Over the whole tree we want the remaining shoots to be the same size. At best, we cut off the small shoots and strong shoots and leave the medium strength ones. Small ones like the one being cut often do not have a big enough end bud to decandle next spring, so smaller is not always better. It still needs to be big enough to decandle.
Next, use a tweezer (or your fingers if on a loose, open tree) and pull old needles. Last year’s needles are usually darker, and arise from below the decandling cut site. The cut site is to the left of the tweezer tip, where the candle was cut in the spring. Pull off the needle pairs, grabbing low on the whitish papery sheath. This action will pull off the sheath as well, which can improve the application of fine wiring. If the shoot is weak, leave some old needles.
When done the 2 shoots should look like this. If the shoots are of different size, then pull some of this year’s needles on the strong one to match that of the weaker one. No need to count them at this time, just eyeball it. Counting needles is part of spring decandling.
Usually we leave 2 shoots on developing pines. But, for trees with few branches and thin foliage, leaving 3 shoots and more needles might be better to keep the tree strong. Later you can cut them back to pairs. And then old bonsai that have been decandled for years may not have room for multiples, or the energy to support them, and leaving only one summer shoot may be best.
A finished branch is open, even, and ready for spring. The success of spring decandling is highly dependent on setting the plant up well the previous fall using these twin techniques: shoot selection, and needle pulling.