Yes, as Chris says, needle reduction on species Pinus thunbergii is possible from over six inches to just under one inch (if you are brave enough). However, most people not familiar with pines tend to try to reduce needle length first shot out of the gun. Needle reduction is a finishing technique and in most cases will just slow down your training plan and general growth.
There are a few cultivars that have shorter needles, although there is also a concomitant loss in growth rate (for most). Probably the finest of the short needled cvs is 'Koto Buki', whose full size needles are about 1 1/2 inch, but the growth is painfully slow on this dwarf. 'Shun Sho' has the shortest needles of all, about 1 inch full size, but the tree's growth habit is fairly normal, making a bizarre looking tree that appears almost fuzzy or furry instead of conifer-like. This can be overcome somewhat with expert training. The best all around short needled, tight internode cvs are 'Yatsubusa' and it's closely related cousins 'Ban Sho Ho' and 'Thunderhead'. Of these three, 'Yatsubusa' is the shortest and tightest. Full size needle length is about 2 to 3 inches, but can easily be reduced to about 1 inch. The beauty of 'Yatsubusa' and to a slightly lesser extent the other two cvs, is its tight internodes and back budding ability. 'Yatsubusa' will break buds internodally almost as easily as in the whorl, and will break buds on quite old wood. Grafting on all of these is not much of a problem, but it still should be performed as low as possible.
Two Nishiki (cork bark) cvs that show good dwarfing characteristics are 'Brocade' and 'Hayabusa'. Full size needle length on these two is nothing to write home about, around 4 inches, but most Nishiki cvs are longer than that, and both of these have a remarkable ability to reduce needle length enormously, to little over one inch. Both have excellent back budding ability and are quite similar to 'Yatsubusa' in growth habit. Additionally, both of these will start forming corky bark at a young age. My two year old grafts are already starting to 'crack' at the base.
Brent
EvergreenGardenworks.com
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