I’m making comfrey tea for the first time this year. Not a tea to drink – although in my extensive Google-based research, I found this somewhat cautionary tale about drinking comfrey herbal tea in large quantities – but a liquid fertiliser for the allotment crops.
Comfrey plants have very long taproots which reach right down into the subsoil, enabling the plant to absorb many trace elements as well as a high concentration of all three of the main plant nutrients: nitrogen, potassium and phosphorus (NPK). I inherited a comfrey patch in the corner of my plot and have used the cut leaves both as a compost starter (chucking the leaves liberally on the heap in between layers of other material) and also to line the trenches when planting potatoes. But until now I haven’t got round to making comfrey tea partly because I haven’t had a spare container and mainly because everyone tells me that it will smell awful.
However with the help of http://www.growveg.com/growblogpost.aspx?id=87 and the acquisition of a spare water butt, I have made a start at making my own liquid fertiliser. The water butt has its tap intact and secure, so is leak-proof, and as for the smell, well, we’re out in the open and can it really be any worse than manure? Lurking in the back of the shed was an ancient hessian potato sack, so I have stuffed this with fistfuls of comfrey leaves, tied up the open end with twine and placed the sack in the water butt. Containing the leaves like this will hopefully stop them from clogging up the tap and will make disposing of them once the tea has brewed a bit easier and less slimy.
Next, I filled the butt with water so that the sack is completely submerged and I have clamped a lid on it – actually a spare water butt stand up-ended and pushed into the top of the butt like a bung. Now the tea is stewing away and should be ready in about a month. There is –as yet – no smell.
If you don't have an off-the-peg comfrey patch to plunder, the plants are readily available in garden centres or you can take root cuttings from friends. If buying, make sure you get Bocking 14 – other varieties are invasive and will self-sow everywhere. Even Bocking 14 is pretty vigorous and you’ll be glad of a reason to cut it down regularly. It also attracts lots of bees when in flower – another bonus.