Hi,trying to purchase comfrey roots to propagate,live in south of Thailand,Nakhon Si Thammarat area.Hoping to use the leaves in my fertilizer program 

Tried this a few years ago. Didn't work. I think it's too hot here for comfrey. Or I made some other mistake. They faded away.

Buy some and try, but don't count on it working.

Comfrey is associated with moist, shady places. I'm not criticising the use of comfrey but conditions are so different here in Thailand, there are certain adjustments you have to make. I worked in landscape gardening for 50 years and much of what I learnt doesn't apply here. 

Tend to agree with you,had a couple of plants both died,think I will look at a more suitable plant for these conditions,Thanks for your input

Cha Phlu (Piper sarmentosum) grows prolifically in semisunny/shaded conditions under Thai weather conditions.  Added bonus is you can eat it (the leaves)