Comfrey – what to do?

Our comfrey plants are thriving – what can we actually use it for?


4 replies on “Comfrey – what to do?”

II. Uses:
Prickly comfrey was evaluated for its value as a forage by the USDA and numerous state experiment stations more than 80 years ago. Comfrey yielded less than some common forage crops and its high water content of 85 to 90%, in comparison to 75 to 80% for alfalfa, made forage preservation difficult. The extensive hairs on comfrey leaves restricts its use as a forage. Fresh leaves are eaten by pigs, sheep, and poultry, but are frequently unpalatable to cattle and rabbits. Cattle and rabbits will eat the wilted forage. Horses, goats, chinchillas, and caged birds are also fed this forage. In a grazing trial in St. Paul, MN, comfrey was judged to be poorly palatable in comparison with several other plant species. This is probably due to the presence of hairs which wilting alleviates.
Wild comfrey was brought to America by English immigrants for medicinal uses. The allantoin content of comfrey, especially in the root, has resulted in its use in folk medicine for healing wounds, sores, burns, swollen tissue, and broken bones. Allantoin, found in milk of nursing mothers and the fetal allantois, appeared to affect the rate of cell multiplication. Wounds and burns seemed to heal faster when allantoin was applied due to a possible increase in number of white blood cells. Comfrey has been reported to promote healthy skin with its mucilage content that moisturizes and soothes, while the allantoin promotes cell proliferation.
The allantoin applied to external wounds is either a 0.4% solution or a 2% ointment. An effective allantoin formulation is difficult to prepare from comfrey due to the low and variable content of this substance. Hart (1976) reported that dried comfrey leaves contain 0.1 to 1.6% allantoin while dried roots have 0.4 to 1.5%. Since fresh leaves are 85% water, they could not contain more than 0.2% allantoin. It would require anywhere from 8 oz to 8 lb of dried comfrey leaves per quart of water to produce a 0.4% solution that would be effective.
Comfrey produces large amounts of foliage from late May until hard frosts in October or November. This crop has been used as a salad green and potherb because it was considered a good source of protein and a rare plant-derived source of vitamin B12. Vitamin B12 is produced usually by soil bacteria and fungi or in the small intestines of some animals. Humans usually obtain this vitamin from eggs, dairy products, and meat. However, a study on the nutritional value of comfrey conducted in Australia in 1983 found that you would need to eat more than 4 lb/day of fresh comfrey to obtain the minimum daily requirement of B12. Eating such large amounts of comfrey, a poor source of vitamin B12, is inadvisable due to the potential health hazards.
Protein content of comfrey dry matter (15 to 30%) is about as high as legumes. Robinson (1983) reported specific amino acid and mineral content of comfrey. Hart (1976) mentioned that comfrey has lower amounts of eight amino acids that are essential for humans than turnip greens or spinach, but more than cabbage. Comfrey, like most green vegetables, is deficient in methionine and is also low in phenylalanine. Three ounces of dried turnip greens or spinach, in comparison to 20 oz of dried comfrey, supply adults with the total daily requirement of all essential amino acids, except for methionine. Comfrey also tends to have high ash content.

Comfrey’s old name is knitbone – if you happen to break a bone or injure a joint, applying a warm poultice of comfrey leaf with bandaging will help it heal much faster. There really is no better treatment for broken toes or ribs, which heal in a matter of days.

A large bunch of leaves broken up and left in a bucket in the sun for a couple of days produces comfrey tea, a great fertiliser. The reason the plant contains such a rich variety of minerals and nutrients is its roots, which grow very deep (metres) and are almost impossible to dig out. It’s these long roots that draw up nutrients from deep rock and soil layers to the surface, and into the plant. This is also the reason to choose your site carefully when planting comfrey – any section of root will quickly sprout leaves, so select a spot where you’ll be happy for it to grow forever.

Comfrey’s also a compost activator – layering leaves beneath mulch or kitchen scraps speeds the process up, breaking organic matter down and making it readily available to earthworms and other beneficial organisms.

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