Unfortunately, comfrey bears a stigma. In the 1970s, scientists discovered the presence of pyrrolizidine alkaloids (PAs) in comfrey that could harm the liver. Panic spreads much faster than prudence or careful research, and soon comfrey had fallen out of favor. The medical community turned against comfrey. Some countries even banned its sale. Some say it’s a conspiracy to push more expensive synthetic solutions on the public. All we know is that even if you don’t eat it, comfrey is too useful to not have around.
Long before comfrey was a scary plant, it was a healing plant of high esteem, used to treat a variety of ills. Most famously, it is used to speed up and ensure proper healing of wounds. Its name is a corruption of “con firma,” which means “made firm” or “to boil together.” The genus name, Symphytum, means “to grow together” or “to unite.” This is a reference to its ability to heal broken bones and reconnect wounded flesh.
It’s been used since the time of the ancient Greeks, and possibly as far back as 400 BC. During the Middle Ages, comfrey enjoyed great popularity as a medicinal herb. During the 1700s and 1800s, it was a common plant in herb gardens. The Russians famously used it for centuries to feed livestock and stave off famine in winter.
Comfrey probably has the widest range of uses in a permaculture system of any plant.
- The leaves are a useful addition to compost or used as mulch, as they contain silica, nitrogen, magnesium, calcium, potassium and iron. Comfrey is lush and fast-growing in the right conditions and can provide abundant supplies of mulch. When planted in the orchard, it can be slashed to provide mulch under fruit trees. Comfrey leaves, measured as dry matter, are about 15 to 30% protein which is as high as most legumes. The leaves readily decompose when soaked in water to make a liquid manure.
- The whole plant is an excellent soil conditioner, the roots penetrate deep into the subsoil and are able to access nutrients beyond the reach of more shallow-rooted plants. This allows the gardener to cycle nutrients leached from the topsoil back to the surface by cutting comfrey leaves and using them as mulch. This deep nutrient mining is particularly useful for the health of soils in heavy rainfall areas. The large, deep roots of comfrey act to break up compacted soils. Plant comfrey downhill from poultry runs or animal pens to trap the nutrients that would otherwise be washed away in heavy rain.
- Weed barrier; one of its more unusual attributes is its ability to stop running grasses in their tracks. When comfrey is planted as a ‘weed barrier’, it should be in a strip several plants wide.
- Animal forage; the flowers are an excellent bee forage. The leaves are nutritious and readily eaten by poultry but should only be given in small quantities. Comfrey has been used as an animal forage for centuries but modern research suggests that in large quantities it can cause toxicity problems for grazing animals. Comfrey contains pyrrolizidine alkaloids (PA). The amount of PAs is highest in the roots. While the level of PAs in a green plant may not be very high, it can be a cumulative toxin. Pigs, horses, goats and cattle are most commonly poisoned by PAs, while sheep are much more resistant.
Try to plant comfrey in the right position the first time as any root disturbance will create new plants. If it has to be removed, simply cover the clump with several layers of wet newspaper and then top with mulch. The comfrey will rot out, leaving a rich, black compost.