Revision Notes

Liquid Feeds – Comfrey Tea. RHS Level 2 R2102.

Liquid feeds are fast-acting as they provide nutrients in a form that is readily available to plants. Comfrey leaves make a liquid fertilizer high in potassium, good for feeding fruiting plants such as tomatoes and peppers. (Nettles may also be used to a create a general liquid feed using method outlined below.)

The RHS examiners define comfrey tea as: ‘an organic infusion where comfrey leaves are soaked in water and used as a fertiliser/liquid/foliar feed’. ‘Bocking 14’ is the variety most commonly grown for garden use.

Equipment Required:


  • A container with a lid and a tap, for example, a water butt.
  • A hessian sack or net bag to hold the leaves.
  • A weight to weight the sack down, for example, a large stone.
  • Clippers or shears to cut the comfrey.
  • Thick gloves to prevent scratches.

Harvesting Comfrey

  • Cut before the plants flower and set seed.
  • Select healthy plants that are free of pests and disease.
  • Comfrey leaves can be cut 4 – 5 times a year down to 5cm above ground.
  • Plants should be well-grown before cutting (e.g. to 60 cm).


  • Put 900g of leaves into a hessian sack along with a brick or large stone.
  • Suspend the leaves and sack in a large volume of water.
  • Leave the sack of leaves in the water for up to four weeks.
  • Strain/remove sack.
  • The remaining liquid tea concentrate can be removed from the water butt via the tap. It needs to be diluted with water before use – 10:1 (water to comfrey).


  • Diluted tea can be applied to the root zone of plants – apply to moist soil.
  • It can also be used as a foliar feed but should be applied in dull weather to avoid leaf scorch.

Leave a Reply

Your email address will not be published. Required fields are marked *