Using Comfrey

David Trammel's picture

Comfrey is one herb that most Green Wizards will want to have in their garden, not just for its medicinal properties but also for its use in the garden on other plants too.

Here's a short introduction to the plant.

How to use the healing herb comfrey

"Comfrey may not be an obvious choice, but it has always been such a kind plant to the garden that it should come as no surprise that is kind to the body, too. Once known as knitbone, Symphytum officinale has a long history of wound healing, particularly broken bones, torn muscles, sprains and aches. It was even applied internally, although many herbalists are cautious of using it this way because it contains powerful pyrrolizidine alkaloids that can cause liver damage and abdominal distress. However, only slight absorption occurs with external application. As such, a compress or poultice is considered more suitable for home use.

Part of comfrey’s magic is down to the presence of allantoin, a chemical that stimulates cell production and thus supports wound-healing. I have read that it was even used in the same way for plants: if a branch was damaged or a graft needed to be hurried along, a wrapping of comfrey was called for to do its wonders.

Its other use, of course, is as a plant food. For every 1kg of leaves, you need 15 litres of water, but it doesn’t need to be precise. Cut the leaves 5cm from the ground, fill a container, add the water and wait four weeks. Then use this liquid on any plant that needs nourishment: once a week for tomatoes, chillies, aubergines, cucumbers, and other fruit in pots once the flowers appear; every other week for other crops in pots and whenever anything in the ground needs a little boost. The leaves are rich in nitrogen, potassium and phosphorous because comfrey’s extensive tap root can mine all the good stuff deep in the soil."

meta4's picture

Apparently people are planting comfrey just to add more minerals to their soil. Seems it has deep roots that pull minerals out of the soil into the leaves. I was watching a documentary where some permaculture guy was continually cutting it back and spreading the leaves. It's an interesting idea but it iseems kind of like "mining" the deeper soils and the longer it's done likely the less effective it would be.

David Trammel's picture

I wonder if you could grow it in soil that has been exposed to toxins and have the plant pulls those up as well? I'm reminded of a past thread, where someone mentioned wanting to green the businesses around them, but that one store had been a print shop and there was a possibility of toxins from earlier print processes in the flower beds.

Also see the thread on Crevice Gardens. If comfrey pulls minerals from the soil, I wonder if it would break down and pull minerals from waste concrete.

alice's picture

Subsoil, in a word. Usually in a cultivated garden the topsoil is only about a foot deep, perhaps a little deeper with double digging or derived from certain geological conditions. So the idea with the deeprooted plants is that their roots dig down below the soil horizons generally cultivated and bring minerals which were not contributing to the garden's fertility into the topsoil which is where the activity is happening. So over time the tendency is for the topsoil to become richer and deeper, both good for cultivation.

[edited for typos]

Don't know particularly about comfrey's use for bioremediation but surveying soil for industrial or natural contamination is a much-needed skill set as I see it. We are going to be dealing with the results of contaminated sewage sludge applications to farmland and the toxic legacy of leaking landfill for a long time yet.