The base is split at the ground into two 6" trunks. One appears to have been pruned close to the ground. The other was cut off about 6' tall.
We moved here in May 2012. I thought the whole thing was a dead trunk that I'd have to dig it up to get rid of.
Next thing, I see shoots coming out everywhere. It bloomed surprisedly grand.
!. I now read where these trees grow to be quite large. It is 15' from the rear of our house. If I'm to move it, will these trees take that well?
2. Since it sprouted and bloomed so well, shall I cut back all growth as it was, or can I prune leaving limbs that will sprout more, giving more blooms?
3. If I wish the tree to grow a bit taller, do I leave only one shoot up-top, or 3 or 4?
4. What kind of root system do these have? The tree is now located 20 feet from the closest septic drain line.
If I can't move it, I'll prune it bare each year, so it doesn't touch the house.
Apparently it thrives on neglect, and is very heat and drought tolerant. In some places it dies back in the winter, in some it doesn't. One person says the roots don't like to be disturbed, which doesn't bode well for moving it. It does sound as if you can prune it to any degree you like without hurting it. It's rated to zone 6 for hardiness, but a couple of people have it in zone 5, which tempts me to try it. I used to have it in a warmer zone, and miss it. It is truly lovely when in bloom, as I was reminded upon seeing your gorgeous pics.
If you want a single trunk tree out of it then it is OK to temporarily keep some of the lower growth, but I would keep removing it a little higher each year until it is as clear as you want from ground to where the first branches start. Keep on training the upper branches to take on the shape you want. At first, this will be a continuation of the single trunk (leave only one at first). When it is tall enough, keep several branches going to branch out and become a small tree.
When the plant puts more energy into fewer branches then each branch grows faster. So, at first, a single main branch, growing vertically to begin making a tree will probably reach a point where you want it to branch out in just one year.
This plant is not really at its best as as single trunk tree, though. It will keep trying to sprout all over, especially low on the trunk.
If you want a multi-trunk tree then do about the same, but allow several main branches from fairly low to grow up and outward in a vase shape. Keep the main branches and prune the new growth to make it look symmetrical and not too crowded. About what the pictures are showing, just remove enough lower growth to see the trunk, if you want that effect.
The way the pictures look now is a large shrub. That is fine, too.