Bonsai tree

Before decandling. Cork bark Japanese black pine bonsai from Bonsai Tonight.
The photos and instructions in this post are all from Bonsai Tonight. The topic is decandling (also called candle plucking or candling pinching) Japanese black pines (specifically a cork bark black pine). The purpose of decandling is to balance bonsai growth, develop ramification and reduce needle size. Not all pines are the same, nor should they be treated exactly the same. Still, the basic principles can be applied to pines other than the Japanese black bonsai.
 
After decandling.

“Divide the tree’s growth into 4 zones depending on vigor. Zone 1 is the weakest, zone 4 the strongest. (See “Decandling basics” for details)
Remove the new growth in zone 2.
10 days later, remove the shoots in zone 3.
Another 10 days later, remove the shoots in zone 4.
The process takes 20 days to complete. How does it work? The longer a shoot has to develop, the more time it has to gain vigor. By removing weaker shoots before removing the more vigorous shoots, we give the weaker shoots more time to “catch up” and grow strong. Stronger shoots get less time to develop – this keeps them in check. The very weakest shoots are left alone. Decandling very weak branches can significantly slow them down or bring them to a stop. Letting them grow for a year increases their strength.”

Source: Bonsai Bark