Comfrey (Symphytum), a member of the Borage family, is a deep rooted plant. The roots provide nutrients to the plant from deep down in the soil. Rich in Nitrogen, Phosphorus and Potassium, the leaves can be cut and used to make a natural. organic, fertiliser which is high in Potassium (NPK: 1.8-0.5-5.3).
If you’ve ever used a commercial Tomato feed then you have used a Potassium rich fertiliser and you’ll probably know that fruits and vegetables can benefit greatly from the use of added Potassium. The fruits of Tomatoes, Potatoes, Peppers, Chillies, Carrots, Cucumbers, Aubergines, Courgettes etc. All need Potassium to grow. Nitrogen is required mainly for leaf growth, so feeding your vegetables from first flowering with a Potassium rich feed is very beneficial. Cabbages, Kale, Spinach, Lettuce, Leeks, Onions and leafy greens will benefit from a mostly Nitrogen rich fertiliser such as “manure tea” that can be made from horse dung.
A good way to tap the Potassium in Comfrey is to steep the leaves in water to make a liquid fertiliser. I have an old wormery that I never really used, but it does have a grill which protects the tap from being blocked by the soaked Comfrey leaves. I simply add water to the container and load it up with cut Comfrey leaves. Keep covered and leave for a week then tap off the liquid. I use it at around half water to half Comfrey “tea” and I usually feed my plants once or twice a week.
You can, if you wish, cut Comfrey leaves and place around your plants as a mulch. The mulch will help to retain water and also provide Potassium as the leaves rot down and the plant is watered. As well as being a great source of potassium for your vegetables, Comfrey can be used to stem bleeding and heal wounds and broken bones., hence the name “knit bone”. The leaves can be soaked in water and wrapped around the wound or bruised area. It is not advisable to drink an infusion of Comfrey in hot water, as this could cause liver damage. The plant may also be carcinogenic if ingested.