Comfrey (Symphytum officinale)

Symphytum is a genus of herbaceous perennial plants in the borage family, Boraginaceae, known by the common name comfrey (pronounced /ˈkʌmfri/, from the Latin confervere to heal or literally to boil together, referring to uses in ancient traditional medicine).

The leaves of common comfrey are dark green, large and hairy, and could be confused with poisonous foxglove leaves before the flowers appear.

Comfrey fruits are four oval nutlets. Common comfrey is about 90 centimetres (3 feet) tall, with winged, hairy stems and blue, purplish, or yellow flowers.

Comfrey is a rich source of nutrients for organic fertilizer. Its deep roots absorb minerals from the soil. Also appreciated as a compost activator, as its leaves are rich in nutrients and can be used to make a powerful liquid fertilizer, often called comfrey tea. A must-have in organic gardens.

Symphytum is native to northern temperate regions of Asia and North America, with a wide introduced distribution on both continents. There are 59 recognized species. More than 150 species have been cataloged by botanists. Some species and hybrids, particularly S. officinale, Symphytum grandiflorum, and S. × uplandicum, are used in gardening and herbal medicine to treat wounds. Also a source of a gum for treatment of wool. Species in the genus Symphytum are different from Andersonglossum virginianum, known as wild comfrey, which is another member of the borage family.

Comfrey contains mixed phytochemicals in varying amounts, including allantoin, mucilage, saponins, tannins, pyrrolizidine alkaloids, and inulin, among others. Pyrrolizidine alkaloids are responsible for comfrey's liver toxicity, which is associated with consuming this plant or its extracts. In modern herbalism, comfrey is most commonly used topically.

Symphytum officinale and wildlife

Symphytum officinale is good for wildlife. Comfrey flowers bloom for a long period (typically May to August) and are attractive to bees. Bee species with long tongues, such as garden bumblebees, are able to access the nectar in the conventional manner, while short-tongued bees will engage in 'nectar robbing' by biting a hole at the top of the flower to get at the nectar. The leaves are the food plant of scarlet tiger moth caterpillars.

How to Grow Comfrey

In the wild, common comfrey thrives in moist, fertile, deep soil (meadows, ditches, and riverbanks) in a sunny position or in partial shade. It grows best in neutral to slightly acid soils. It's a vigorous grower and sets seed readily, so it's unsuitable for all except the largest gardens. Once established, it can be difficult to get rid of as sections of root left in the ground can develop into new plants.

Plant comfrey in spring (or autumn) in well-prepared ground free of perennial weeds. Mulch with organic material such as garden compost topped with leaf mould to conserve water and prevent the growth of weeds.

Common comfrey isn't particularly susceptible to pests or diseases, and requires little attention once established. Make sure the soil doesn’t dry out, especially when young plants are becoming established. As leaves can irritate the hands, it's advisable to wear gloves.

Make sure you plant it in an area where it won't outcompete less vigorous plants.

If you choose to grow from seed, make sure you chose a non-sterile comfrey, such as common comfrey.