Family: Boraginaceae or Borage family
Comfrey is a valuable herb for organic and permaculture gardens. It is one of the best known and effective Dynamic Accumulators which improves the soil by mining minerals with it’s deep fibrous roots.
Comfrey is commonly used to improve soil for the benefit of other plants. It is a perennial plant and will grow back even when all its leaves are removed for use. It has broad leaves and is a clumping herb which grows vigourously but does not spread. The plant is generally low to the ground and provides a good ground cover to keep the soil moist and support soil biodiversity.
Soil Improvement. Comfrey specifically accumulates Potassium (K), Phosphorus (P) and Calcium (Ca) as well as Copper (Cu), Iron (Fe) and Magnesium (Mg). The leaves can be harvested and used by:
- Scattering over the soil as a surface mulch;
- Mixing into a compost pile;
- Digging into the topsoil to add organic matter and nutrients;
- Making liquid fertiliser or weed tea by adding to a barrel of water with other leaves.
Some people use the leaves to brew a tea, but you should take care and do your own research as some scientific research has indicated compounds in the leaves can cause cancer.
Common Comfrey, Symphytum officinale, has narrower leaves and a more vertical shape and therefore does not have some of the advantages of the Russian variety.
For more information, you could start here: Wikipedia