Improving your soil and plant growth with comfrey feed.

 Improving your soil and plant growth with comfrey feed.

Plant fertilisers such as Tomorite or Chicken pellets are getting increasingly costly to buy and sourcing suitable manure and transporting it to the farm is hard work. Increasingly at HCF we have become aware of the potential of growing our own fertiliser- Comfrey. When Andy Waterman first proposed growing it around the Old Fruit cage several years ago there was opposition from some team leaders, so we grew it in large pots for a few years before planting a small comfrey patch near the strawberry polytunnel. Demand for liquid fertiliser is increasing as are the potential uses and so the places where we are beginning to grow it are increasing.

Bocking 14 Comfrey 

Why is Comfrey so useful?

Leafy vegetables need lots of Nitrogen , Root vegetables need lots of Phosphorus (P), flowers and fruits need lots of Potassium (K). Or as Gareth Evans, my old Botany lecturer would say

“N for shoots, P for Roots, K for fruits.”

Comfrey is as good as Tomorite for plants such as tomatoes, peppers, and beans as well as greedy feeders like potatoes plus fruits such as strawberries, gooseberries and raspberries as the table shows.

In addition, it compares well with manure and compost:

One square metre will produce around 7 kg of comfrey a year which can be cut three or four times during the season and so a large biomass of plant material can be produced from a small space. The wonderful benefit of Comfrey is that it has extremely long roots which can mine nutrients from several metres below the surface and which would otherwise be totally unavailable to vegetable crops. The disadvantage is that once comfrey is growing the roots are difficult to kill off and the plant lasts for over 20 years. So don’t ever plant comfrey in a place if you might sometime later want to move it somewhere else.

How to grow comfrey.

We use a variety called Bocking 14 (developed in Bocking, Essex) which is a sterile hybrid clone of two Russian forms. Bocking 14 doesn’t set viable seed, but does spread slowly if not checked back. To make more plants a plant is cut up, the leaf removed and the stem and upper area of the root cut into small sections a few centimeters long.These are allowed to grow roots and leaves in a pot containing a light compost. The young plants are planted out into a cleared area of ground where they are expected to grow. Planting distances are approximately 60 cm between plants.

Comfrey growing along a fence line made of old pallets

How to use comfrey

There are several ways to use Comfrey.

Rotting comfrey at the bottom of a bucket

Toby Turl has recently introduced a new method of makes a concentrated liquid feed. He cuts the leaves and puts them in a bin with a hole at the bottom. As the comfrey breaks down liquid drains through the hole into a small container below which collects the concentrated liquid. He makes a litre every couple of weeks and this is diluted about 10 times over before being watered on plants.

Adding comfrey to a compost bin to speed up composting

I cut comfrey leaves, mixing them with pernicious weeds (nettles, couch grass, docks, dandelions and thistles) and toss them into a sack in an old rubbish bin which has been filled with water. After a few weeks when I need some liquid feed I push my watering can into the bin, draw up half a can full of liquid, dilute it further with water and pour onto my fruit bushes. After a couple of months all the comfrey and weeds have broken down in the sack, so I draw out the liquid for use on the plants then tip the completely dead slime into the compost bin or onto a plot. This is a much speedier method than cold composting and there are no viable seeds or pieces of root which will find their way back onto the soil.

Another use for comfrey is as a surface mulch on blackcurrants and raspberries. I use the “chop and drop” method. First chop your leaves, then lay a 5 cm mulch of the leaves on the soil around the plants. Within a couple of weeks the leaves will have gone black and within a month they will have disappeared completely. This mulch slows down evaporation of moisture from the soil and suppresses weeds. As the comfrey leaves wilt they attract slugs and snails, possibly from feeding on surrounding valuable plants and so reduce damage. Hopefully then, the slug will be devoured by a hungry ground beetle or blackbird.

So there are several ways in which we can use this most helpful of plants on our community farm.