Rakh, the folklorist observatory keeper, who has a thing for plants
(treehugging ex-ranger) found out something while tending his plants. He
discovered a technique for conserving the plant used in casting the various
herbal spells. This technique, known as 'knowledge of herb conservation', is
now being taught to those who have excelled in their studies. Rakh, being the
low-brow he is, isn't too good a teacher, so, the cost of training is rather
high. Find the busy (yeah, right) Rakh and ask him about help.

Good luck in your studies!
Folklorist Headmaster Heidel