Comfrey grows wild on many allotment sites as is a fast growing (and spreading) perennial which will if 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.
is the most popular of these teas and we would recommend all composters to make it to supplement their composting and compost teas.
Comfrey is a good source of potassium and nitrogen. Comfrey tea promotes the development of flowers and fruit and
is best applied once the first flowers have set. It is recommended for use on tomatoes and peppers.
The most common method of 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. Use a conatiner with a lid to contain the smell.
Either use a container with a tap or a hole in the bottom, so that the fertiliser drips into a catch-pot or remove the liquid from above with a watering can. An old 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 throughout
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.