Comfrey: growing, care & uses

Comfrey is an ancient medicinal herb that bumblebees adore. Here is a quick introduction to the plant, as well as instructions on how to grow it at home.

Comfrey (Symphytum officinale) has been used for thousands of years for its healing powers. It is a native wild herb that grows in lush meadows and along forest edges. Read on for an overview of comfrey’s diverse uses and step by step instructions on how to grow this valuable herb.

Comfrey origin and properties

Comfrey is a native perennial and medicinal plant. In a suitable habitat, the plant can live for up to 20 years. The genus Comfrey (Symphytum) is made up of about 40 species native to Eurasia and North Africa and belongs to the Boraginaceae family. Common comfrey (Symphytum officinale) can be found from Spain to China.

It is an herbaceous perennial plant that dies back in winter, but the roots remain, and it sprouts again in spring. Its roots reach down to a depth of 1.80 metres, and, above ground, it grows to a height of about 30 to 60 centimetres. The stiff stem and large deciduous leaves are rough and covered in bristly hairs. Such features are typical for members of the borage family like forget-me-nots (Myosotis), lacy phacelia (Phacelia tanacetifolia) and viper’s bugloss (Echium vulgare). The flowers, which hang down in double coils, resemble small bells and are purple, yellow or white.

Depending on the variety and location, comfrey flowers from May to October. Only bees with long proboscises can drink the nectar from the flowers, which is why bumblebees (Bombus sp.) and other large wild bees are the most common visitors. However, most of the flowers are sterile and rarely form seeds. Comfrey mainly reproduces via runners of its rhizomes.

Species and varieties

Comfrey can be divided into several species that are used either as medicinal plants, fodder plants or ornamental plants. Here are the most important species and varieties:

There are many subspecies, such as white comfrey (Symphytum orientale), common comfrey (Symphytum officinale) and Bocking 14 or Russian comfrey (Symphytum x uplandicum). Aside from common comfrey, forage comfrey (Symphytum asperum), which was introduced from the Caucasus, is also commonly found in Europe. This species is considerably taller than common comfrey, reaching heights of up to 180 centimetres. It was introduced as a forage plant for livestock in the 16th century because it has less harmful pyrrolizidine alkaloids. Russian comfrey (Symphytum x uplandicum) is a hybrid developed from common comfrey and forage comfrey. This hybrid form contains no harmful alkaloids. Russian comfrey is not only used in feed but is also used medicinally in capsule form for human consumption. Symphytum azureum, an ornamental species, has particularly beautiful sky-blue flowers. In many perennial nurseries you can find different varieties of creeping comfrey (Symphytum grandiflorum), including ‘Miraculum’ (red, pink and white flowers), ‘Hidcote Blue’ (red buds and pale blue flowers) and ‘Blue Bells’ (large, lavender-blue flowers and red buds).

Growing comfrey

There are few options for growing comfrey at home: you can sow seeds, propagate it by division or purchase young plants from nurseries.

Sow comfrey seeds in March in nutrient-poor growing soil such as our Plantura Organic Herb & Seedling Compost and keep them on a warm windowsill. In warm climates, sow the seeds directly outside from April onwards. The sowing depth for the seeds is 5 centimetres. When pre-cultivated indoors, comfrey germinates somewhat irregularly and needs to be transplanted into more nutrient-rich soil, such as our Plantura Organic All Purpose Compost, after about three weeks. In May, move the young plants to their final location, where they will take root over the summer and then be ready to brave the winter.

An easier option than sowing is to divide an existing perennial. In spring, use a sharp spade to cut off a part of the plant that has both roots and buds, and then plant these in a new location. Yet another option is planting pre-grown plants from a nursery or garden centre. When planting comfrey, take care not to damage the rhizomes and use quality potting soil to fill in the spaciously dug planting hole.

Comfrey can be propagated again from its own seeds. However, the seeds are rare, since most of the flowers are sterile. To propagate comfrey from its seeds, collect the seed stalks in autumn and bring them indoors to dry. They can be sown the following spring. However, as mentioned, propagation through root cuttings and plant division really is the much easier option.

The right location

When planting comfrey, find it a spot in a semi-shady to sunny area with moist, humus-rich soil. An ideal location is under the canopy of an old tree, where the plant can find the humus-rich soil it needs.

Comfrey plant care

Comfrey hardly needs any care. As native plants they are very adaptable and undemanding. When growing comfrey in your garden, however, there are a few things to bear in mind for watering and fertilising.

Watering

Comfrey plants love moist, well-drained soil. Water it frequently, particularly in the first year after planting, as dry soil spells death for this medicinal plant. Water older plants regularly during exceptionally dry summers.

Tip: A layer of mulch will keep the soil moist much longer and save you litres of watering.

Fertilising comfrey

As a perennial plant, comfrey often grows in the same spot for many years. So, replenish the soil nutrients with some fertiliser from time to time, especially if the plant is harvested regularly. In spring, work some universal fertiliser, such as our Plantura All Purpose Plant Food, into the soil to meet the needs of comfrey. Alternatively, use some mature compost to deliver nutrients to the plant.

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Comfrey uses

With a long history as a medicinal plant, comfrey is still frequently used today in ointments. But did you know it can also be used as a fertiliser?

Comfrey: uses in the garden

Comfrey leaves can be fermented to make a nutrient-rich plant slurry. The main nutrients it provides are nitrogen, phosphorus and potassium as well as a lot of micronutrients and silicic acid. The liquid compost is used to fertilise and strengthen plants against pathogens and pests in a ratio of 1:10 in irrigation water. When harvesting comfrey to make fertiliser, only pick the non-flowering shoots and no more than four times a year. This way, the plant stays strong and can be harvested from for years to come.

Medicinal uses

Common comfrey has been used as an herbal medicine since ancient times. A couple of early names for comfrey were ‘knitbone’ and ‘boneset’. These are references to one of the most important applications, bone healing. Symphytum is from Greek and also translates more or less to “growing-together-of-bones plant”.

The root or, more rarely, the leaves are used for healing. Both contain mucilage, saponins, tannins, allantoin and pyrrolizidine alkaloids, which when consumed are toxic to organs and tissue. Comfrey creams and ointments should therefore only be used externally and not applied to open wounds. Because comfrey has an analgesic and anti-inflammatory properties, the ointments, gels and other extracts are mainly used for rheumatic pain and for sports injuries such as strains and sprains.

Tip: Make your own comfrey ointment
To make your own ointment, first prepare an oil extract. To do this, soak some chopped comfrey root in olive oil for four to six weeks in a closed container. Then heat the oil with beeswax to make an ointment.