I read this frrom a book on African Violets by a British author. She says that roots > 0.5cm become water roots. Water roots cannot change to breathing roots and but short breathing roots can become water roots if you put them in water long enough. Since water roots can't breath in soil, too many of them will cause them to rot and perhaps get infected. There are instances when I was too lazy to cut roots etc, but I find that if I have enough pertiles in my soil mixture, they do fine. I also sut them in clear plastic containers for 2 weeks just after potting.
