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Organic Fertilizer - Comfrey

comfrey, organic fertilizer

How to use Comfrey as a fertilizer.


Comfrey has many uses as a medicine, as well as being used as a fertilizer It is an East European native plant, although it has now been introduced to many other parts of the world. Comfreys healing properties have given rise to various names such as 'Knitbone'. The leaves of the Comfrey plant have small hairs which can be irritating to some people, but when the leaf is rolled in on itself these hairs can knit together like a weak form of Velcro. The leaves can also be applied directly to cuts and bruises, by firstly dipping them into boiling water to sterilize them, and when cooled placed over the wound. The active ingredient in Comfrey which heals wounds is Allantoin, which is a cell profliferant which speeds up the natural replacement of body cells. Comfrey has also been used to treat bronchial problems, broken bones, sprains, arthritis, gastric and varicose ulcers, severe burns, acne and other skin conditions. Constituents of comfrey also include mucilage, steroidal saponins, tannins, pyrrolizidine alkaloids, inulin, vitamin B12 and proteins. Internal usage of Comfrey should be avoided as it contains Hepatotoxic pyrrolizidine alkaloids which have been linked to veno-occlusive disease, or the blocking of small veins in the liver.


Comfrey is a dynamic accumulator which extracts the nutrients in the soil and can then be used as a fertilizer. It's root system can grow up to 10 feet down to extract nutrients from places which other plants cannot reach. Other dynamic accumulators include, Borage, Bracken, Clovers, Stinging Nettles, and Yarrow.

To use Comfrey as a fertilizer there are several options. Firstly they can be used straight from the plant as a lining for trenches or as a simple mulch, they can also be mixed with water and used as a liquid manure, or they can be incorporated into other composts. My favorite method is to cut the leaves and place them in a large water butt, with no water. The leaves will break down quickly and produce a black (very smelly) liquid, which can be diluted (15:1) with water and applied to crops.

Nutritional Analysis

Comfrey Liquid Feed versus Commercial Liquid Feeds %
  Tomorite Marinure Comfrey
Dry Matter 0.1410 0.0480 0.4090
Nitrogen 0.0130 0.0070 0.0140
Potash 0.0139 0.0019 0.0340
Phosphorus 0.0093 0.0001 0.0059

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