Fresh herbs, or sometimes even preserved herbs, are hard to come by in large quantities. Knowledge of herb conservation helps you squeeze the last ounces of power out of herbs, thus saving the herb for another use. The skill is automatically in effect when casting herbal spells. Fresh herbs are easier to save, but a master of this skill should have no trouble saving even non-fresh herbs. Strong preserving magics, on the other hand, render the herb unconservable. Some herbs are considerably harder to conserve than others.