Though it has suffered from a lot of bad press throughout the years, comfrey is becoming well known for medicinal use, as well as its use as a “dynamic accumulator” companion plant, fertilizer and herbal insecticide, far outweigh its reputation as an “invasive spreader.” The key to keeping comfrey in its place is as simple as putting up a “Do not disturb” sign. When the roots of the comfrey plant are disturbed (through tilling or hoeing) it triggers a self-preservation response from the plant, causing more energy to go into the root system to ensure its survival.