If you have space in your garden for a comfrey, they make a good fertilising brew for the rest of the garden. Just soak comfrey foliage in water for a couple of weeks until it’s slimey and stinky… More instructions here
What is brilliant about comfrey is that it contains high levels of all the essential nutrients for plant growth: Nitrogen, Phosphorus and Potassium (NPK) together with many other trace elements. Comfrey out-performs manure, compost and many liquid feeds for concentration of nutrients. It produces these from a deep root system extending right into the subsoil that most edible plants cannot access. It also has an ideal Carbon:Nitrogen ratio which means that it does not hamper absorption of nitrogen by plants. When cutting comfrey it is advisable to use gloves as the hairs on the stems can irritate skin.
You can do likewise with nettles which supply a nitrogen-rich soup which benefits roses, tomatoes, roots vegetables, legumes – colours, plant growth, flavours and textures all seem to improve. Nettles have deep roots and as they grow, they also bring up trace elements from the deeper soil which are essential to plant health but which are often lacking in regularly cropped top soil.
We actually make a mixture of comfrey and nettle fertliser.
Comfrey flowers are also pretty: