I bought a bottle of Comfrey Ferment a long time ago and used it during veg and the first few weeks of flower. It’s smells horrible and I saw no benefit from using it.
I only tried once so that’s where I’m coming from.
Hope this helps.
I have only heard about this in passing and have not done it.
It is part of KNF correct??
If so, I think it can't hurt to try it. Might be a waist of time or might be ok.