Page 32 - ALG Issue 3 2019

Liquid Feeds from Comfrey and Nettles
These provide a natural source of
plant nutrients and an alternative to chemical fertilisers and pesticides, which may harm insects, wildlife, plants and the soil. Fermented or plant teas are typically produced by soaking undecomposed plant leaves and shoots in unchlorinated water for two or three weeks. During the fermentation period, dissolved oxygen will reach low levels, encouraging microbial anaerobic growth – but not for the full two to three-week soaking period, and some aerobic organisms will return to activity as oxygen returns. The fertiliser is best diluted using unchlorinated water such as rain water. Generally, the fertiliser should be diluted so that it looks like weak tea; normally ten-parts water to one-part tea.
Plant teas, which can be applied by watering or spraying, are a good source of nutrients. It can be used unfiltered as a drench applied directly to the soil or filtered as a foliar spray. Filter using an old pair of tights, cheesecloth or burlap.
• Nitrogen(N)stimulatesleafgrowth.
• Potassium(K)orpotashpromotes
developing flowers and fruit.
• Phosphorus (P) enhances root
growth.
Comfrey grows wild on many allotment sites as it 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.
COMFREY TEA
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 three to five weeks. To make a good concentrated fertiliser the leaves should be pressed down into the container by a weight on top such as a brick of broken paving slab. Use a container 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
every two or three months. Or, once
the liquid is used, add the sludge to the compost bin to help keep it moist and act 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 diluted version.
I recommend that it is made using a drainage pipe fitted 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 sparkling wine bottle which is heavier and more fun to empty before use in the tube! Larger quantities of concentrated comfrey tea can be made by packing
32 Allotment and Leisure Gardener