Growing & using garden Comfrey
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Use In The Garden
The plant's deep roots accumulate potassium from subsoil. It's leaves are high in nitrogen too. You can make a concentrated liquid containing all of the big 3 nutrients: nitrogen, phosphorus, and potassium, in substantial amounts. A high potash feed, it has an*N : P : K of about 8 : 2.6 : 20.5 %.
Place the plant's leaves into a large container, preferably one with a tap or hole at the bottom, and a tight lid at the top to exclude water and flies as well as keep any smell inside. Fill the container with leaves e.g. an empty Can-O-Worms container will do the job, filling the bottom module with tap, as well as the upper modules. Cut the leaves before the flower buds appear and before the ageing leaves develop infections. (I normally exclude rust infected leaves if I'm going to give any of the liquid away, otherwise rust is simply 'part and parcel' of the herb's life.)
A block of wood and a brick could be placed on top of the pile to press it firmly and gently down, (without crushing). Fresh Comfrey leaves contain more nitrogen than farmyard manure and a black liquid smelling of ammonia will soon collect in the bottom. It is drained off into a screw topped collecting bottle. The solution needs to be diluted 15 - 20 times with water before application in the garden (giving N.P.K. = 0.5 : 0.4 : 3.8. - a high potash feed.
(How to correct the nutrient balance).
Ready made fertilizer
The liquid is a versatile fertilizer, easily stored and transported, and applied to plants by watering or spraying. The nutrients it contains are readily available and it should therefore be applied carefully in small quantities or it will be wasted.
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FEED TO TOMATOES AND PEPPER PLANTS
While Nitrogen stimulates leaf growth, excess potash somewhat stunts growth and coarsens leaves, but it promotes developing flowers and fruit. It is therefore important to apply the liquid fertilizer only after the first flowers have set. Regular feeding may then support better flower and fruit development. The liquid feed is more important for plants grown in pots, rings or containers than for plants in good garden soil. Container grown flowers have a limited food supply, for which there is usually stiff competition. Liquid Comfrey is ideal for encouraging flowers. Again it is probably best to delay application until the plants have grown a good set of leaves. Although the high potassium content in this liquid fertilizer promotes flowers and fruit, it may be considered too high for general use. It can however be adapted by mixing with other garden-made fertilizers.To make a more evenly balanced fertilizer may I suggest mixing 1 part Comfrey liquid with about 19 parts worm tea for an estimated N.P.K ratio of 2.5 : 2.2 : 2.5 % - then dilute. (This assumes that worm tea has the same composition as the worm casts and of course worm casts will vary in composition according to how the worms are fed.)
How to make worm compost at home
Alternatively dilute 1 part Comfrey concentrate in 15 - 20 parts water before application. Alternative ready to use organic liquid fertilizers - U.S.A. - are available online here. Apply them as instructed on the label.
Get your soil tested and
get an organic feed customised
to your soil requirements.
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Experiment - try digging up a Comfrey plant to harvest roots as well as leaves; chop up and add to worm composter. I'm speculating that the phosphate composition in the roots may be higher than in leaves. The worms will certainly make this phosphate more available. I can't back this with a proven result but it seems to have much to commend it. It's probably best just to mix in some of the chopped roots into the normal feed rather than add a larger amount of the leaves, as the ammonium may be too strong for the worms?
^ Top of page Mix equal parts - chopped Comfrey leaves with well decayed autumn leaves - and a little calcified seaweed to increase pH and add growth stimulants. This gives a rich potting compost suitable for transplants, potting etc... but too rich for growing seedlings. Spread a 2" layer of fresh Comfrey leaves over the top of a new compost heap, give a sprinkling of water, and cover this with a thin layer of fine soil. The fresh leaves ( with *C/N ratio = 10 ) contain more nitrogen than farmyard manure ( with C/N ratio=14 ). So adding it to compost will quickly get the microbes busy. If using it as a substantial component of the compost heap remember to balance this with equal parts brown material like shredded straw or dead leaves to achieve the otpimum C/N ratio for bacteria of 25 to 30. Don't add the living roots to compost; kill by drying them out first, othewise they will spread.
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Cultivating Comfrey In The Garden
FEEDING YOUR PLANTS
Legumes such as Alfalfa take nitrogen from bacteria which in their turn fix nitrogen from the atmosphere. But Comfrey, just like Brassicas, gets all its nitrogen from the soil. Therefore, to keep the plants and the soil in 'tip top' condition, nitrogen feeding is necessary.
This can be done by mulching with animal manures, and any grass cuttings in excess of composting needs. Alternatively fork in part of a green manure crop such as Alfalfa or grow Clover (another legume) permanently around your Comfrey. If you keep pet animals that use part of the garden as a toilet then encourage them to occasionally use the Comfrey patch for droppings which you then cover with soil. Avoid long term application of urine as it increases the salt concentration and reduces worm activity. If you use the plant as a herb or medicine take care not to contaminate anything you will consume.
The trick is to manage Comfrey as part of a natural cycle, to turn otherwise lost or unavailable nutrients into an organic plant form. Then to use the plants as a rich organic fertilizer to augment other sources of nutrition and boost fertility. The plant is able to combine nitrogen (that you might waste) and otherwise unavailable or lost potassium in subsoil, into an organic form. For the organic gardener, increasing nutrient rich organic matter and replacing nutrients lost at harvest time are two important goals.
Other organic plant foods.
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For a small to medium sized garden a bed of 4 - 8 plants spaced 2-3 ft apart (1-2 ft on poor soil), makes a start. When the plants are established sow Clover between and leave the cut Clover as a mulch. The patch might be conveniently situated near to your compost heap but preferrably in a sunny position.
You will find that once established a Comfrey plant will be hard to get rid of (see eradication method below). So before you plant it you need to decide on a permant growing position for a plant that has an expected lifetime in excess of 20 years.
Plants used for garden cultivation are usually taken from the Bocking cultivar of Russian Comfrey (Symphytum x uplandicum) exported to U.S.A. and Canada in 1954. This plant rarely sets seeds and so it won't infest your garden. Any of the plants offered for sale from seeds are unlikely to be suitable, at least not for the purposes described on this page. Look for Comfrey sold as root cuttings or offsets.
The plant roots or offsets are set out from March to May or in September. Place offsets with a growing points just under the surface or roots about 2" deep. Keep watered for a few weeks until plants are growing.
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REMOVING COMFREY PLANTS FROM THE GARDEN
The plant can regenerate from pieces of its roots, and these grow deep. Choose dry sunny conditions to dig the whole plant up taking care to remove all roots from the soil. Then persist in cutting down any new growths as soon as they appear until the plant is erradicated. This could take a couple of years depending on how thorough you are.You can try selling the products of from your patch to other gardeners or divide the plants and swap for new plants (take care not to share the plants if Club Root Disease has been found in the same soil).
*N.P.K. stands for the ratio of Nitrogen : Phosphorus : Potassium
*C/N ratio is the ratio of Carbon to Nitrogen; around 30 is ideal. Dry, brown, or woody matter has more carbon and higher C/N ratio, sappy, green matter has more nitrogen and lower C/N ratio.
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Further Information
