Compressed Comfrey Tube.
The bucket would normally be covered with polythene to prevent it filling with rain water
It is easy to make plant-based liquid feed extracts using comfrey, stinging nettles, horse tail or clover. Comfrey grows wild on many allotment sites as is
a fast growing (and spreading) perennial) which will given half a chance take over the whole site. For this reason I would recommend buying root cuttings of the Bocking 14 variety. Do not take root cuttings from other plants unless you know it is B14 or it
has been grown in situ for a number of years and has not made a take over bid for the site.
Comfrey is the most popular of these teas and we would recommend
all composters to make it to supplement their composting and compost teas.
The most common methodof making comfrey tea involves soaking the leaves in water but this is the method that produces the famous stinking
liquid feed. A barrel or tub is quarter filled with comfrey leaves topped up with water and allowed to stand for 3 to 5 weeks. To make a good concentrated fertilizer the leaves should be pressed down into the container by a weight of top such as a brick
of broken paving slab.
Either use a container with a tap, a hole in the bottom, so that the fertiliser drips into a catch-pot, or remove the liquid from above with a watering can. A Bokashi bin makes an excellent container
in which to ferment comfrey tea as the filter tray prevents the leaves from blocking the drain tap and the airtight lid contains the smell.
There are two approaches to maintaining a supply of feed through
out the summer. Either keep replacing the water as it is used and top up the supply of comfrey ever two or three months. Or once the liquid is used add the sludge to the compost bin, to help keep it moist and as an activator, and start again using the fresh
growth that has replaced that which you cut.
Be warned comfrey liquid produced in this way smells very unpleasant. Use the tea diluted, one part tea to three parts water, for established
plants, either watering into soil or as a foliar spray. For younger tender plants, such as tomatoes dilute one part tea to ten parts water and only water into the surrounding soil or you may scorch the plants.
Concentrated comfrey tea
Concentrated Comfrey tea has the advantage of not smelling anywhere near as much as the dilutes version. I recommend that it is made using a drainage pipe fiited with an
end cap through which a single drainage hole has been drilled. Comfrey leaves are compressed in the pipe using a plastic bottle filled with sand or water or a sparking wine bottle which is heavier and more fun to empty before use in the tube.
Larger quanitities of concenrated comfrey tea can be made by packing comfrey leaves into a barrel or a similar container with a tap, preferably compressing the comfrey down with a spade to get the maximum amount into the barrel and compressing
it with a weighted lid. Only add a small volume of water or urine and water to get the flow going. This method is recommended by Nicky Scott in How to Make and Use Compost (Green Books 2009)