In article , Peter Sutton
writes

Its a huge subject, and I was really only questioning the speed at which
roots form. I had always assumed that they grew at a linear rate, ie after
10 days the roots were twice as long as after 5 days. But my recent
observation implies that for 10 days nothing appears to happen, then two
inch roots can suddenly grow in only two or three days.




I would suspect (please note I am a non-technical person!) that for the
first few days the cutting can use the salts etc from the sap in the
actual stem and then the cells at the base click over to root
production.
I thought this was what happened as sometimes you can keep a cuttings
going for quite a while especially if long, however in the end the
cutting never produces roots and then dies.
So I assumed it was getting enough sustenance as it were, to exist for
so long.
Like trees and shrubs that get uprooted but flower or come into leaf
before dying eventually.
On the other hand this probably labels me as a right nitwit in the
propagating department
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk