Fill a bucket with fresh, roughly chopped comfrey leaves. Pour boiling water over the leaves to wilt them.
Top up the bucket with cold water and cover loosely. A black plastic rubbish bag is ideal. Do not use a tightly fitting lid as the gases that form will cause it to explode.
As it matures, it will start to stink, so keep it away from the house.
After 4 weeks strain into bottles.
To use dilute 1 cup in 10 litres water