Comfrey is a perennial plant that can be used as a natural fertilizer for many plants:
Comfrey leaves
Can be used as a mulch, powder, or steeped in water to make a liquid fertilizer:
Mulch: Spread cut leaves on the soil around plants.
Powder: Use comfrey leaves as a powder.
Liquid fertilizer: Steep chopped comfrey leaves in water for 4–12 weeks to create a dark, smelly liquid. You can dilute the liquid with water and apply it to plant roots.
Comfrey tea
Steep comfrey leaves in water for 8–12 weeks to make a thick, brown-black tea.
Compost
Add comfrey leaves to your compost to increase the nutrient content and speed up the composting process.
Getting comfrey with growing my own fertilizer | The ...
Comfrey is a good source of nutrients because it has a deep taproot and large root system that can reach nutrients in the subsoil. It's high in nitrogen, phosphorus, potassium, and other trace elements. Comfrey's high carbon to nitrogen ratio means it doesn't deplete nitrogen from the soil as it decomposes.
Comfrey liquid manure works well for heavy growers like tomatoes, eggplants, cucumbers, pumpkins, potatoes, peppers, celery, fruit plants and zucchinis. It can also be used for berry bushes, lovage, fruit trees, roses, and sunflowers