Comfrey (also comphrey) with a black, turnip-like root and large, hairy broad leaves that bears small bell-shaped white, cream, light purple or pink flowers which bloom from May to October is an important herb in organic gardening, having many medicinal and fertilizer uses. It is a native herb in Europe and temperate Asia, thrives in damp meadows and shady places by rivers and streams throughout Britain and has long been known as a medicinal herb. It was cultivated by both the Greeks and the Romans. It’s botanical name is Symphytum officinale and it is a member of the Boraginaceae family as are Borage and Forget-me-not. The name Comfrey is a corruption of ‘con firma’, which ties in with its old common name of Knitbone. The botanical name, Symphytum, is from the Greek symphyo meaning ‘to unite’.

Nicholas Culpeper, the famous herbalist, knew of comfrey and said: 'The great Comfrey restrains spitting of blood. The root boiled in water or wine and the decoction drank, heals inward hurts, bruises, wounds and ulcers of the lungs, and causes the phlegm that oppresses him to be easily spit forth.... A syrup made there of is very effectual in inward hurts, and the distilled water for the same purpose also, and for outward wounds or sores in the fleshy or sinewy parts of the body, and to abate the fits of agues and to allay the sharpness of humours. A decoction of the leaves is good for those purposes, but not so effectual as the roots. The roots being outwardly applied cure fresh wounds or cuts immediately, being bruised and laid thereto; and is specially good for ruptures and broken bones, so powerful to consolidate and knit together that if they be boiled with dissevered pieces of flesh in a pot, it will join them together again.'

He also considered it beneficial in the treatment of haemorrhoids and said: 'The roots of Comfrey taken fresh, beaten small and spread upon leather and laid upon any place troubled with the gout presently gives ease and applied in the same manner it eases pained joints and tends to heal running ulcers, gangrenes, mortifications, for which it hath by often experience been found helpful.’

Comfrey (Symphytum officinale ) is used to treat wounds and reduce the inflammation associated with sprains and broken bones. The flower was used in the Middle Ages to help relieve lung problems caused by black death. The roots and leaves contain allantoin, a substance that helps new skin cells grow, along with other substances that reduce inflammation and keep skin healthy. Comfrey ointments were often applied to the surface of the skin to heal bruises as well as pulled muscles and ligaments, fractures, sprains, strains, and osteoarthritis.

A reputable medicinal herb, it has been used as an astringent to arrest bleeding. A poultice made from crushed leaves cleans wounds, reduces swelling and bruising and unites fractured bones, hence its local name 'Knitbone' and 'Bruisewort'. A tea, made by immersing the roots and leaves in boiling water, is drunk to soothe chest complaints and ease coughs. The young leaves, finely chopped, can be scattered over salads, cooked like spinach or used in Comfrey fritters, made by dipping the whole leaves in batter and deep frying for two or three minutes. It is an ideal composting plant as it causes the rapid breakdown of other plant material.

Warning: Internal usage of comfrey should be avoided. Repeated doses of Comfrey may be dangerous. In recent years, this long used herb has come into disrepute.

Historically, comfrey was also used to treat gastrointestinal illness. However, the herb contains dangerous substances called pyrrolizidine alkaloids that are highly toxic to the liver and can cause death. In July 2001, the U.S. Food and Drug Administration required that dietary supplement manufacturers immediately remove all oral comfrey products from the market. The United Kingdom, Australia, Canada, and Germany have also banned the sale of oral products containing comfrey.

Pyrrolizidine alkaloids are also absorbed through the skin, and harmful amounts may build up in the body. New advise says that you should take care when using an ointment containing comfrey, and you should never use it on broken skin.

Cultivation

The comfrey bed should be well prepared by weeding thoroughly, and dressing with manure if available. Offsets should be planted 2–3 feet apart with the growing points just below the surface, whilst root segments should be buried about 2 inches deep. Keep the bed well watered until the young plants are established. Comfrey should not be harvested in its first season as it needs to become established. Any flowering stems should be removed as these will weaken the plant in its first year. Comfrey should also be regularly watered until well established.

Comfrey is a fast growing plant, producing huge amounts of leaf during the growing season, and hence is very nitrogen hungry. Although it will continue to grow no matter what, it will benefit from the addition of animal manure applied as a mulch, and can also be mulched with other nitrogen rich materials such as lawn mowings, and is one of the few plants that will tolerate the application of fresh urine diluted 50:50 with water, although this should not be regularly added as it may increase salt levels in the soil and have adverse effects on soil life such as worms. Mature comfrey plants can be harvested up to four or five times a year. They are ready for cutting when about 2 feet high, and, depending on seasonal conditions, this is usually in mid-Spring. Comfrey will rapidly regrow, and will be ready for further cutting about 5 weeks later. It is said that the best time to cut comfrey is shortly before flowering, for this is when it is at its most potent in terms of the nutrients that it offers. Comfrey can continue growing into mid-Autumn, but it is not advisable to continue taking cuttings after early Autumn in order to allow the plants to build up winter reserves. As the leaves die back and break down in winter, nutrients and minerals are transported back to the roots for use the following spring.

Comfrey should be harvested by using either shears a sickle or a scythe to cut the plant about 2 inches above the ground, taking care handling it because the leaves and stems are covered in hairs that can irritate the skin. It is advisable to wear gloves when handling comfrey. Despite being sterile, Bocking 14 Russian Comfrey will steadily increase in size. It is therefore advisable to split it up every few years (and at the same time propagate more plants that can be shared with fellow gardeners!). It is however difficult to remove comfrey once established as it is very deep rooting, and any fragments left in the soil will regrow. Rotovation can be successful, but may take several seasons. The best way to eradicate comfrey is to very carefully dig it out, removing as much of the root as possible. This is best done in hot, dry summer weather, wherein the dry conditions will help to kill off any remaining root stumps. Comfrey is generally trouble free once established, although weaker or stressed plants can suffer from comfrey rust or mildew. Both are fungal diseases, although they rarely seriously reduce plant growth and thus do not generally require control. However infected plants should not be used for propagation purposes.

There are no known scientific reports of interactions between comfrey and conventional medications. Some herbs that have also been known to cause liver problems, such as kava, scullcap, and valerian, should not be used while using comfrey ointment or cream because of the increased potential for liver damage.