Symphytum officinale

Common Comfrey (Symphytum officinale) is an ‘unsung’ hero - especially for the non-organic gardener, and considered by many as a weed.  It is not a particularly attractive plant but it deserves praise for the role that it can play within any garden.
 

Symphytum officinale is an upright perennial attaining a height of around 1.5 metres that produces purple/pink/cream flowers in spring and summer.  However, the flowers, which are attractive to bees, are not the main feature of the plant; it is the large hairy grey/green leaves.

They store high levels of nutrients (potassium and trace minerals) of which can be harvested as a fertilizer for plants in the garden.  Comfrey also has its uses as an edible and medical plant.


History

Comfrey’s ability of nutrient absorption has earned it its place in organic gardening due to its cheap and invaluable uses within the garden.  These uses were researched by Lawrence Hill, the founder of the Henry Doubleday Research Association (HDRA) which formed in 1958.  The HDRA was aptly named after Henry Doubleday who introduced Comfrey into Britain in the Nineteenth Century and he aimed at popularising the plant during his lifetime.  The HDRA continued the study of Comfrey and ways in which to improve organic gardening.  Some of Comfrey’s uses are highlighted below:

Comfrey - The compost heap activator

Comfrey is great on the compost heap as it increases the rate of composting of other materials on the heap.  Its high carbon content is priceless when the compost heap consists mainly of fresh foliage (and subsequently a high nitrogen content).  In addition, the trace elements that are absorbed by the comfrey go into the compost heap and therefore improve the quality of the compost produced.

Comfrey - The green mulch

Comfrey leaves act wonderfully as a green mulch; retaining moisture, suppressing weeds and supplying nutrients valuable for potash-hungry crops like tomatoes. 

Comfrey - The liquid fertiliser

Comfrey leaves produces a potassium rich liquid fertiliser which works brilliantly with potash-hungry crops.  Although a foul smelling liquid it is a cheap fertiliser and an essential tool, especially for the organic gardener.  To make the feed you will need (sounds like something off Blue Peter) a container like a bucket or water butt, comfrey leaves and water.

 

Simply take the leaves, tear them up and add them to your container - so that it is loosely full - and pour as much water as can be held by the container, leave this is ‘stew’ covered for a couple of weeks and hey-presto.  When it is ready (usually four weeks) you will be left with a rich brown liquid that unfortunately has a foul stench but this is a good indicator of when it is ready.  This solution should be watered down when required and used as a liquid feed, I usually do half comfrey solution to half water but this is all dependant on the strength of the solution.

Propagation

One of the reasons why the plant is considered by some as a weed is due to its ability to self-seed; this can be seen as a relatively easy way of natural propagation and a good way to boost plant numbers.  However, for those that do not wish to be removing unwanted plants from around the garden seeds can be sown in pots in autumn or spring under a cold frame.  Alternatively, Comfrey can be grown from root cuttings taken winter or by division in spring.

Cultivation

This is one of the beautiful features of Comfrey in that it can be grown in pretty much any soil condition or aspect meaning that a place can be found for it anywhere in the garden (and in our hearts).  From experience of growing Comfrey I will say that it will need some support; although when it does fall over (and it has attained a decent height) I treat this as a sign to harvest the plant.

Care

Comfrey is a low maintenance plant and requires very little care.  Harvesting is best done before flowering, as this stops the plant self-seeding and the nature of the plant allows multiple harvests each year (sometimes up to four a year).  Enriching the soil with nitrogen will improve the plant quality as Comfrey extracts nitrogen from the soil.

Pests and Diseases

Generally pest and disease free and I have yet to encounter any, however they can encounter rust or mildew but this rarely seriously reduces plant growth.