rjj, I don't quite understand what you are getting at either. if you could post a couple pictures it would be very helpful.
Randy is talking about exactly the same thing as Gnome & I [+ repeating the chop later with no sacrifice ]
one question - how would keeping a sacrifical lower branch add vigor and growth?
Sorry, I see how that sounds a bit cryptic.
It may be more accurate to say it: It puts growth where you want it [In this example, The trunk.]
This way your tree is not wasting it's resources on growth that is not beneficial to your goals.
Brent from EGG has a bit to say about it, This is from https://evergreengardenworks.com/trunks.htm:
Growing Sacrifice Leaders and Branches
A related process is to grow sacrifice leaders and branches to increase trunk or branch caliper, or correct a reverse taper in a developed tree. This process involves growing a wild whip somewhere out of the trunk, or less frequently, out of a branch to increase the caliper up to its point of attachment. The difference in this case, is that the sacrifice is simply a tool, an artifice, that will be removed completely when it has done its job of increasing the caliper. Sacrifice branches can be used for deciduous or evergreen trees, but they are especially important for developing conifers.
It is important when growing out sacrifices not to shade out the areas below it , or overly weaken the areas beyond it. I usually let the sacrifice grow as a long unpruned whip with all the leaves and small branches cut off of it for several feet to keep from shading the 'tree' below. Sacrifices can be as long as ten feet or more, depending on the degree of enlargement desired.
Use sacrifice branches and leaders to correct a problem when your tree already has good form and finished branches. Remember that branches increase trunk caliper up to their point of attachment. To increase the diameter along the entire trunk allow a sacrifice branch to grow near the apex of the tree, but not at the very tip of the apex or it will destroy its delicate structure. If this occurs you will have to grow a new apex to achieve the final diminishing taper. I often cut out the sacrifice before it has finished its job and start a new one a little lower to preserve taper.
You will have to remove your tree from its pot and put it in the ground or in a larger training pot to achieve the vigor necessary for the sacrifice branch to do its job. To achieve caliper and taper, select positions lower on the trunk for the sacrifice branches. Do not let sacrifice branches grow from existing branches (water sprouts) or you will overly fatten the branch and put it out of proportion to the trunk. They can, however, be used to correct the diameter and increase vigor of weak branches.
When sacrifices are used to strengthen branches as well as the trunk, one must be much more careful. Development can come very quickly, and overdevelopment can occur in a single season. Overly large branches are a common fault and are difficult to correct. If overly large branches occur, all you can do is place a sacrifice above the fat branch to increase the trunk size to restore the balance.
Essentially, The unrestricted growth of a sacrificial branch helps the trunk increase in girth which in turn helps to achieve taper. This is why you would let the leader develop unchecked also [And then possibly re-chop it as Randy mentioned
- will if I prune it severely down to 2 branches, 1 as new leader and 1 as sacrifical branch, would it survive the process?
Absolutely, This IS how bonsai are constructed/grown.
- if I am to do this pruning, when should I go about this? is there a time period I should do this around?
For your ficus it should make no difference though if you do not have good lighting you might wait until it can live in some bright sunshine.
Brighter=tighter growth and shorter internodes.
- after pruning, how would I take care of it? I'm assuming less water but still aimple sunlight.
Right you are [It may need less frequent watering but still do check every day]
oh so many things to do and too read and look up
I am excited to do some actual work on my bonsai instead of just making sure they don't die