May, Jun, Jul, Aug, Sep
Harvest comfrey leaves from the base of established plants. The hairy leaves can irritate the skin, so wear gloves if necessary.
Remove flowers and tough stems, then chop up the leaves and pack them tightly into a water-tight container. If possible, choose a container with a lid, as the solution can smell as the leaves break down. Use a brick to weigh down the leaves.
Check on the progress every few weeks. The leaves will break down gradually, releasing a smelly brown liquid. Collect any liquid, storing it in a cool, dark place. Top up with fresh leaves.
Dilute the collected liquid at a rate of one part comfrey to 10 parts water - the darker it is, the more you'll need to dilute it. Use the solution as a potassium-rich liquid fertiliser to encourage flowers and fruit set.