how to grow comfrey plants and make liquid fertiliser

What is comfrey?

Comfrey is a member of the borage family. A strong-growing perennial with 12" to 18" long hairy leaves on short stems growing from a central crown.
It has a pretty blue bell flower that fades to pink. The plant can reach a height of over two feet with a spread up to 3 feet across.
The comfrey plant has medicinal uses. However, this article is about its use as a plant food.

  • What is Comfrey used for?    
  • Its uses in feeding garden and container grown plants.
  • How to make comfrey liquid fertiliser.
  • How is it good for plants?       
  • How to grow my own comfrey plants
the comfrey plant
the comfrey plant

Why is Comfrey liquid fertiliser good for feeding plants?

  • Comfrey has deep roots that bring nutrients up from deep down in the ground.
  • The nutrients are stored in the leaves and are rich in nitrogen and potassium with some phosphorus as well. 
  • The leaves are also full of silica, calcium, iron, magnesium and other essential nutrients to help plants grow and stay healthy.
  • Comfrey leaves when used to make liquid fertiliser makes a really unbeatable natural slow release plant food.
  • Over-feeding plants with manufactured fast-release fertilisers causes a quick burst of unnatural growth leaving the plants vulnerable to pests and disease similar to the hit unhealthy fat people get when eating burgers and cola.
  • On the other hand Comfrey is a slow release natural food.

The benefits of feeding plants with homemade Comfrey liquid fertiliser

Over-feeding your plants with off-the-shelf fast-release fertilisers often causes just the opposite to what is intended, a quick burst of unnatural growth leaving the plants vulnerable to pests and disease.

On the other hand, plants that are fed with a slow release natural food like Comfrey liquid. Grow normally, will be healthy and more able to resist most attacks by pest or disease.


Adding plenty of organic matter to the soil and the occasional feed of Comfrey liquid fertiliser provides all the food garden and container planted fruit, vegetables and flowers need. Feeding to much fast-release fertiliser is a bit like feeding kids a diet of fast food and sugar, providing a short burst of energy, but leaving them unhealthy in the longer term.


Plants grown in containers, hanging baskets or poor garden soil will benefit from feeding a slow release natural food getting the best from them in both quality and quantity.

What nutrients do plants need that Comfrey liquid feed provides?

  • Nitrogen that encourages green growth, 
  • Potassium encourages healthy flowers, vegetables and fruits, 
  • Phosphorous is an essential nutrient to encourage healthy roots. 

Whilst it is rare for garden soil to be noticeably deficient in any of these. Very sandy, very acidic soils, or soil that has been used for intensively grown crops can be deficient, and will benefit from regular mulching with home-made compost from your heap and a feed of Comfrey liquid. Garden vegetables grown close together because of a lack of space will also benefit from a dose of potassium.


Signs of potassium deficiency to look out for. Are a bluish tinge to older leaves, yellowing between the veins of leaves. And if left to late, stunting of growth and a failure to produce many fruits or flowers, but if spotted early and fed with a potassium-rich feed like comfrey liquid, the plants will recover. Some plants like tomatoes and potatoes are very sensitive to low potassium levels. The tomato fruits, can remain green and hard and sometimes hollow. Potatoes, may turn black when cooked.


Why buy artificial potassium-rich feeds when it is so easy to make your own using comfrey leaves. I have explained how to make comfrey liquid feed below, or if you prefer, buy it from a neighbour gardener or supplier who makes their own.


Calcium. Plants need calcium for the growth of its young roots and shoots. Without calcium, plants can't grow. However, calcium deficiency in the soil is very rare. Not watering evenly (to dry, then to wet) is the main cause of calcium deficiency. Comfrey is very effective at taking up nutrients and goodness from the soil and storing it in its leaves. So no reason to overfeed your garden plants with artificial off-the-shelf fast-release fertilisers. Tap into nature's store and keep your plants health and productive in a natural way..


How to grow Comfrey plants to make liquid fertiliser

  • Planting and growing Comfrey. Comfrey will grow on most soil types, but doesn't like chalky soil, doing particularly well in good rich organic soil in full sun. 
  • If you plant seedlings in spring you will be getting your first leaf harvest before the end of the growing season. Allow about 2ft between plants. 
  • Maintenance. Once established, it needs very little maintenance. However, to maximise your comfrey crop, extra feeding with manure and compost or grass clippings will all help produce more leaves. Remove flowering stems in the first season to gain maximum leaf growth next year.
  • Root cuttings. In subsequent years comfrey plants can easily be grown from root cuttings. Cut 2-6 inch lengths of healthy root and plant horizontally 2-8 inches deep.
  • Follow link for Comfrey plants and seeds from Amazon

How to make liquid fertiliser from home grown comfrey plants

  • Cut the stem at ground level and strip the leaves into a bucket. Hold the comfrey leaves down with a brick or large stone and then top it up with water.
  • The rotting leaves in the bucket will gradually turn into a sludge.
  • After three weeks, strain it through a garden sieve into a waterproof container with a secure lid to make a liquid feed. Before using the comfrey liquid fertiliser, dilute it with water to a ratio of 1:10 and apply either to the leaves or roots.
  • You can also put the leaves onto the compost heap or directly onto the soil as a plant fertiliser.
  • Best to wear gloves when handling comfrey, as the stems are covered in stiff hairs that can irritate the skin.
  • You can cut comfrey throughout the growing season stopping in September to allow a final autumn growth before winter.

Can I buy Comfrey fertiliser?

Yes you can purchase it now, if you don't have the time to make your own, I recommend this one litre pack of pellets, simply add water to make up to 75 litres. Store pellets in a dry place and the pack will last a long long time.

Just follow the simple instructions on the pack to make a Natural plant feed and soil conditioner. NPK, trace elements, vitamins, minerals and hormones. Buy it now before the rush...