The key to reducing Buttonwood foliage, as well as with just about any tree, is
"mass". By this I mean the more foliage a tree has the smaller the leaves will become
due to the fact that the tree does not need to produce larger leaves to retain light...
So, More leaves... smaller size... Remember This !!!
So, to answer both of your questions... Evmibo and Dario...
I leaf cut Bottonwoods. By this I mean I cut the all the leaves on the tree in half with
scissors. Some of the larger leaves I will cut even more. What this does is that the
tree recognizes the leaf has been damaged, and sends out new growth to repair the
damage. By maintaining the partial leaf though, the tree still is able to maintain it's
intake of light, so that it does not put the trees health in jeopardy, like defoliation
would.
Now as far as when to do this and how often ??? This depends solely on the tree's
responds... Some trees can be done all the time, by this I mean, when the new growth
pops up and reaches a size larger than the previous cut growth, I cut the new growth.
Some trees are a little more sluggish to respond, they just don't push the new growth
as fast... and then you would want to back off a bit. Let them grow to their full size,
maintain that full size for a while to build up the strength of the tree, then cut and see
how it responds.
I have quite a few Buttonwoods... One of my large ones, the one I posted a video about
http://bonsainut.com/forums/showthread.php?11483-Rather-Large-Buttonwood
I go through and leaf cut this thing almost every week !!! You want to talk about a pain !!!
I have another that is even bigger it's 4 ft, that I have done alot of work on lately, styling,
and carving, the whole front of the tree is deadwood. It obviously is alot slower to respond
because of the recent work done to it, so I had to back off...
As far as what time of the year to start ??? I again just let the tree tell me... During
winter the tree slows down obviously... when spring comes and it starts taking off I
let the new growth go for a couple of weeks to a month, just to let it build up it's energy
and then begin... This winter however where I am at was very mild so I didn't have to
wait to long. I think I started in Feb-March.