A few years ago I created some cork bark black pines by grafting. The trees have grown well and are now quite full.
Corkbark Japanese black pine
Some of the oldest needles have recently begun to yellow which is a tip-off that the interior branches will be yellowing out as well.
To make sure that the interior branches receive enough light to stay healthy, I thinned the trees out by removing about a third of the foliage.
Thinning the tree out like this makes the structure apparent at a glance. Over the next year or two, I may make a few decisions about the future size and style of the tree, but for now I want it to continue growing to increase the size of the trunk.
The other two trees from this group got the same treatment – minor cutback, the removal of very few needles, and no decandling.
Tree 2 – after cutback
Tree 3 – after
If you’re curious to see how these trees have developed from the beginning, see the following articles here.