the term you are looking for is: rejuvenation pruning ...

i have no experience with this plant.. so i googled it for you ...

it does not involve what you are thinking ... most plant have dormant buds.. that will trigger when a large branch is cut.. but it might take half the summer... but the key is usually that you want this to happen low to the ground... as you dont want a whole new bush.. at height... the stub left.. will eventually fail ... unless you are really thorough with followup pruning ...

hit the link.. while you are waiting for specific replies...

all that.. or the common rules of shrub pruning dont apply to this plant.. and i will be chastised mercilessly ....

ken

Here is a link that might be useful: link

Much more shrubby in nature than tree-like, removal of the lower branches generally results in a bare trunked specimen. Woody plants that will sprout from low on the trunk (under existing branches) are limited and if this was one, would have done so already. In most cases, new branch growth will only appear on the upper portions of the plant.

Try planting something low and leafy and shrubby in front of the pitts to hide the bare legs. It's about as good as you are going to get.

Yes, my backup plan is to plant alphonse karr bamboo, which I am also using as lower screening (not second story) elsewhere. Since it probably would not do well under the trees, I should also take out one more pittosporum (leaving two for second story screening) to give the bamboo enough sun.

I just need to talk my wife into it, which at the moment is a monumental task. I was hoping to do something with our existing trees, but looks like our neighbors screwed us there. Maybe in a couple of years when she decides it's time to plant something, who knows?

The bamboo can tolerate partial shade easily. And it can - in time - provide sufficient height for even second story screening. You might want to also check out various Fargesia species - another clumping bamboo and very shade tolerant. And a range of heights available, depending on species.