I've got a couple of Rex begonias - names unknown but commonly available. I can divide them ok and have even been able to grow some from a split leaf. But I've never been sure how deep to plant the rhizome (?). I've got all of the gnarly bits and stubs above the soil line in the pots because I wasn't sure if they would rot. Should they be planted deeper? I looked at some of the links for this forum but have only just started on that amazingly thorough list. I would appreciate any helpful tips.
How deep to plant rex begonias
Yes keep the rhizomes above the soil line else you might cause it to rot.
Thanks so much for the advice! One other question - since my lumpy rhizomes are exposed, is it possible to trim off any excessively protruding stubs that aren't producing leaves? These poor rhizomes are a testament to being ignorantly ignored.
You can but that might take away energy from the plant. If you do I'd dust the wound(s) with some anti fungal powder and place the cut rhizome on a bed of moistened perlite to see if it will set roots and grow you a new plant.
Do remove any rotted or dried pieces.