Comfrey

 Comfrey 

Comfrey is a tall, perennial, herb plant, also known as boneset because it was used to heal broken bones. The word comfrey comes from the Latin word for "grow together". It is a member of the Boraginaceae family, which also include borage, forget-me-nots,

The plant grows well in damp places and can stand full sun.  The common plant can easily get out of control in a garden, so would not normally be deliberately introduced unless it was a really large garden.  In the 1950s the organic pioneer Lawrence Hills (founder of the organisation now known as Garden Organic formerly the Henry Doubleday Research Association (HDRA)) developed a strain of Russian comfrey named Bocking 14 which is sterile and won’t seed itself all around the garden. 

It can be propagated by root cuttings although my patch is spread so well I have never needed to do it.

 What makes it a Good Fertilizer?

Comfrey has deep taproot, and large root system which pulls nutrients from way down in the subsoil, where most other plants can't reach. Comfrey is high in just about every nutrient a plant needs, including the big 3, Nitrogen, Phosphorus and Potassium, and many trace elements. It can be used as a ‘Mineral Dam’ utilizing minerals that would usually be washed away by storing them in the leaves.

Its high carbon to nitrogen value means that it does not deplete nitrogen from the soil, as it decomposes. In fact, it becomes a good source of nitrogen. And it has more potassium than composted manure.

You can use the leaves in 3 main ways: as a liquid feed, as a compost activator or straight into or on the soil as a plant fertiliser, there are variations on this and here are a few.

Comfrey Uses

Fertilizer - Comfrey leaves contain a great balance of major plant nutrients (N,P,K) and can be feed to plants as powder, direct mulch or by steeping chopped Comfrey leaves in water for several weeks to produce a thick, dark liquid that can be diluted with water and applied to plant roots. I’ve decided to only use this outside this year and not in the tunnel as it can be very smelly.

As a trench fertiliser and as a mulch - Line potato or bean trenches with comfrey leaves and cover with a thin layer of soil. After planting, fill the trench as usual, and the comfrey leaves will be broken down by the soil bacteria to provide a potassium-rich fertiliser. Alternatively place a layer of leaves around the growing plants. This will not only slowly rot down to provide nutrients, but also act as a mulch to help control weeds.

Comfrey compost activator and leaf mould - Place cut or bruised comfrey leaves in alternate layers throughout your compost heap. This will encourage bacterial action causing the heap to heat up and speed up the composting process. This could make a fine medium for growing seeds although small amounts are recommended as it can be a bit strong for seedlings.

Medicinal Use - Comfrey has been cultivated, at least, since 400 BC as a healing herb. The Greeks and Romans commonly used Comfrey to stop heavy bleeding, treat bronchial problems and heal wounds and broken bones.

Biomass - Comfrey produces large amounts of foliage from late May until hard frosts in October or November. The plant is excellent for producing mulch.

Biodiversity  - The bell shaped flowers provide nectar and pollen to many species of bees and other insects from late May until the first frosts in late Autumn. Lacewings are said to lay eggs on Comfrey and Spiders overwinter on the plant. Parasitic Wasps and Spiders will hunt on and around Comfrey.

Pest and Disease Prevention and Control - Research indicates that a comfrey solution can be used to prevent powdery mildew. Pest predators such as spiders, lacewings and parasitic wasps associate with this plant. Its best to leave some plants alone in order to sustain pest predator relationships.

Ground Cover – Some species can quickly spread to form a thick ground cover and work particularly well for ground cover on the sunny side under shrubs and trees. Symphytum tuberosum - Tuberous Comfrey is a great ground cover option. 

Animal Fodder - Comfrey has a long history for use as an animal feed. Fresh leaves can be eaten by pigs, sheep, and poultry but cattle, rabbits and horses will usually only consume wilted leaves.

Human Consumption - Symphytum officianale  and Symphytum x uplandicum are both reported to be used for salad and potherb and are best when cooked. I won’t be trying it myself though. I’ll stick to nettles.