If you have a willow tree around, they contain a naturally occurring rooting hormone. Here is one link about making "willow water" for rotting purposes:
https://preparednessmama.com/willow-rooting-hormone/
Alternatively, powdered hormone is cheap, and using it with some sort of plug that the roots can grow into will give you very good results. Then you plant the plug, and that avoids the problem mentioned above of the roots collapsing. Plugs can be made of rockwool, coco peat, or just a bit of moist pro mix. Anything can work as rooting media, as long as it holds air and water.