Russian Comfrey, a Useful Plant for Gardeners

Comfrey is a large perennial plant in the Boraginaceae family, of which there are around thirty species. It is very common in Europe in damp meadows, undergrowth and old gardens. Comfrey has been used for centuries in traditional medicine, but also to improve soil fertility in the garden. Several species originated in Eurasia and spread throughout Europe, probably via pilgrims and “travellers” who used it to heal their wounds along the way. In the New World, the first settlers imported comfrey to cultivate it in their medicinal plant gardens.

Sterile Hybrids

Unfortunately, most species are highly invasive, and Larry spoke of them as loathsome plants in an article published in 2019. However, in the 1950s, a British agronomist, Lawrence D. Hills, created sterile cultivars from Russian comfrey (Symphytum × uplandicum), which comes from a natural cross between two species: S. asperum and S. officinale. This hybrid was first described in Sweden in 1854. Fascinated by the virtues of comfrey, but concerned by its invasiveness, Lawrence D. Hills carried out experiments at his research station in Bocking (Essex) and selected some twenty cultivars. The Bocking no. 14 cultivar would be particularly interesting for the garden, and the Bocking no. 4 ideal as fodder for farm animals.

It’s probably a Symphytum × uplandicum ‘Bocking 14’ seedling that I myself received from a member gardening club in the 1980s, as my comfrey plants have been quiet in their corner for decades and only reproduce if I divide the plants to share with friends.

What Does Comfrey Look Like?

Comfrey is a large plant that can grow to over a metre (3 feet) in height, depending on the species, with vigorous roots 1 to 2 cm (1/2 inch) in diameter that can extend to over a metre (3 feet) deep if the soil conditions permit. Its large leaves are lanceolate and very rough. The drooping, tubular flowers form scorpioid cymes, changing color from creamy-pink to blue as they bloom.

A Medicinal Plant

Comfrey has been used since time immemorial to treat sprains and even fractures, at a time when medicine was rather rudimentary. But it is still used today in herbal medicine, especially in ointment form, for its haemostatic, anti-inflammatory, astringent, healing and emollient properties. The French name “consoude” comes from the Latin consolidare: to consolidate, to heal, and “Symphytum” from the Greek: to weld.

An Edible Plant First Challenged, Then Cleared

In Europe, comfrey is used by connoisseurs to feed farm animals such as poultry, pigs and large livestock. However, its consumption is still the subject of debate following a study carried out in Australia in 1970, which presented comfrey as dangerous due to the presence of alkaloids toxic to the liver. This claim was disputed by the same Lawrence D. Hills and the HDRA. Hills and the HDRA. According to him, there had been confusion with heliotrope, another borraginaceae much richer in alkaloids and truly toxic.

On the Passeport Santé website, we read: “… Several of the seven cases of harm reported in the scientific literature were related to excessive and prolonged consumption of an unspecified variety of comfrey. On the other hand, a clinical study involving 29 subjects demonstrated that long-term consumption (1 to 20 years) of comfrey did not cause liver damage.”

Nevertheless, Health Canada advises Canadians not to consume health products containing comfrey due to the risk of the presence of unsaturated alkaloids of the pyrrolizidine type and, therefore, the risk of liver damage.

Caution is therefore called for, and the subject of this article is gardening anyway.

*HDRA is the acronym of a very famous association in England: the Henry Doubleday Research Association, which L. D. Hills founded in memory of another ardent comfrey supporter. The HDRA is now known as Garden Organic.

A Gardener’s Friend

Comfrey is a wonderful melliferous plant much appreciated by bees, but also by all the pollinating insects of course, such as bumblebees, butterflies, hoverflies and many others that will pollinate the flowers of our crops and help the production of our vegetables whose flowers are not always very conspicuous.

‘Bocking 14′ comfrey is particularly popular as a natural fertilizer. This variety is very rich in potassium (K), an essential element for flowering and fruiting plants. It also contains nitrogen (N), phosphorus (P), calcium, magnesium and other plant-benefiting trace elements.

Comfrey can also be used in the form of a liquid manure. Like nettle purin, comfrey purin can stimulate natural soil fertility and plant growth. If nettle is rich in nitrogen, comfrey brings more potassium to the garden. The method is the same: roughly chop 1 kilo of fresh plants in a plastic bucket, add 10 liters of water and leave to macerate for around 2 weeks, stirring daily with a wooden stick. In summer, the process can take as little as a week. It doesn’t smell very good, but only when stirred. Cover the bucket anyway to prevent odors or small animals from falling in.

After a week or two, filter and dilute the liquid at a rate of at least 1:10 before spreading on the soil (never on the leaves) around the plants. Comfrey purin is said to be particularly beneficial to species whose fruit or tubers are harvested, such as tomatoes or potatoes. Some gardeners bury comfrey leaves when planting their greedy vegetables. Nettle manure, rich in nitrogen, can be used alternatively, but especially around leafy vegetables such as lettuces and cabbages.

Others use comfrey leaves as mulch, as the plant produces an abundance of large leaves and they can also be used to enrich compost.

Don’t plant comfrey in a small vegetable garden, as even the sterile comfrey ‘Bocking 14’ takes up a lot of space. But it’s a lovely decorative plant to use as a background in a large perennial bed.