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I can also recommend using rhubarb leaves either on their own or in with comfrey leaves to make an excellent natural and free fertilizer - again the smell is horrendous and almost makes me retch but the effect on plants is remarkable. The rhubarb soup also has the added benefit of scaring off a number of bugs (probably the smell!). I make mine in an old dustbin with lid which I found in a skip.
I've been making Comfrey fertilizer for a couple of years by soaking the leaves in a large plastic pelleted chicken manure container. I have not found it neccessary to put any weight on top of the leaves but a tight fitting lid is essential to contain the bad smell. I have calculated the volume required to mix with a 2 gall. watering can and cut the sides of an old tin down so that it just holds that amount. This is attached to a stick so that I can dip out the correct amount every time.
Terence Jones
What are the acual values of Comfrey liquid manure?
Terence Jones

Has anyone analysed the NPK ? If so what does it show.

Can you use green alkanet if you dont have comfrey in your garden as I have an abundance of it?


from garden organic website-- "Comfrey

There has been much written about the humble Comfrey plant over the years by people with differing opinions. Some see it as a rampant weed others as a decorative addition to the flower border. For the organic gardener it is the most valuable non-food plant available and one that EVERY gardener should grow.

There are many ways to use comfrey; as a mulch, compost accelerator, as a high nutrient compost ingredient, as a ‘tea’ or as liquid plant food. More on this later but before we get down to practicalities it might be useful to know something of the history of how Comfrey came to be recognised as a star of the organic garden.

In 1954 Lawrence Hills, the founder of HDRA now Garden Organic, began researching the use of Comfrey. He found that because it ‘mines’ nutrients using its deep root system, the plant is very rich in the basic N-P-K (Nitrogen, Potash, Phosphorous) elements which are the basis of all fertilisers and are essential for plant health and vigour. Comfrey no doubt contains useful amounts of trace elements but nobody seems to have researched this.

Hills went on to develop the most useful variety of Comfrey, Bocking 14, which was named after the location of the trial grounds in Essex. The most important property of Bocking 14 is that it is sterile. That means it does not self-seed so does not spread like wild Comfrey. Having said that once you have Comfrey in the garden you will never get rid of it as even the smallest fragment of root seems to grow vigorously.

In his book “Comfrey, Past Present and Future” Hills listed the results of analysis of Comfrey grown at Bocking.

Comparative Nutritional Analysis of comfrey, compost and manure

Material Water % N% P % K % C:N Farm Yard Manure 76.0 0.64 0.23 0.32 14:1 Wilted Russian Comfrey 75.0 0.74 0.24 1.19 9.8:1 Indoor Compost 76.0 0.50 0.27 0.81 10:1

He also made Comfrey juice by using 14lbs of comfrey leaves in a 20 gallon drum. Again the results of the analysis are shown below.

Material DM N P K Tomorite 0.1410 0.0130 0.0139 0.0093 Comfrey 0.4090 0.0140 0.0340 0.0059

DM – dry matter, N – Nitrogen, P – Potash, K – Phosphorous

This really does show that Comfrey is a very useful and valuable plant to have in the garden. By pressing the leaves and thin stems, and waiting for the evil smelling, dark brown juice to appear, it is possible to make a fertiliser as good as the best commercial brands. Not only is this a free source of nutrients for the garden it also fulfils one of the basics of organic gardening, sustainability, by creating a closed system."

I find the analysis of tomorite v Comfrey tea very interesting. Especially since I can harvest bagfuls of comfrey from the river bank for free. I am currently stewing up a dustbinful.


I would also advise using gloves when cutting comfrey. The hairs irritate some peoples skin. Also as I didn't my hands look like I have a 60 a day fag habit, and I can't get rid of the stain. I've used skin scrub, soap, swarfega, soaking. it's going to have to wear off.

Adam, thank you for the tip. Which of these liquid feeds made of leaves makes a low nitrogen fertilizer suitable for Geraniums?
Following Monty Don's recent suggestion I made nettle and comfrey fertilizer. The nettle is ok but the comfrey is teeming with white maggots with tails. What are they? Should I bin the whole bucketful?

drone fly maggots or rat tail maggots. Just drain the juice off to use and dump the rest of it on the compost heap.


I have around 90 comfrey seedlings growing in my polytunnel at home that will soon be planted out onto my plot.  I have a strip of stoney ground down the side that is against a fence with trees behind so is in shade for a large part of the afternoon.

Before I switched plots two years ago (moved to a plot three times the size) I used to have one waterbutt solely for making comfrey tea.  Nothing scientific - I would simply rip the leaves up and leave them in the water with no lid.  I'd add some to a watering can - depending on its colour.  It did smell a tad but the taste of tomatoes, peppers and beans made up for it!  In the summer I cut them down almost to the ground for the compost heap.  I noticed the other week that they are still on the plot and about 4 feet tall!

Without comfrey and nettles this year I've been using Tomorite and it's not as good.  Last year was a washout so I can't really compare.  Next year I will be back to being wholly organic as I bought a comfrey plant from the local garden centre - I couldn't wait 


you can cut comfrey up to six times a year. If you pack it dry with a weight on it doesn't smell as much.  Once you have comfrey you will not get rid of it without weedkiller.


You can also make comfrey tea with two buckets:

Put holes in the bottom of one bucket and place the leaves in that (under a weight).  Put this bucket into the second one.  When the comfrey leaves break down (no need to add water) the resulting liquid drains through the holes into the second bucket.  This should be diluted by about 15 to 1.  

From what I've read the undiluted liquid has an NPK of about 8.0 - 2.6 - 20.5


You shouldn't apply comfrey tea until flowering as the high potassium can stunt growth due to a nitrogen defficiency.  Too much potassium can also trigger a magnesium defficiency which is often confused with blight.

R Mark  Welsh
I make my own by placing 8 comfrey leaves stalk first into a empty cleaned 2 Litter drinks bottle. I then add rain water from my water butt to about 2 inches from the top, then replacing the top to the bottle this I then shake daily! it takes about 8 wk/ks for the leaves to break down !I made my first batch Last year seemed to work well I add a small amount to a watering can witch I then fill with rain water, this I leave over night to allow the liquor to homogenise 'activate the full can of liquid feed for use the following morning'... repeat m


can you use this feed in hanging baskets and tubs.

Potassium is good for fuits and flowers so I'd say yes.  I've used it in pots for peppers with only positive results.

Is it high or low nitrogen fertilizer? I want to know how to make a natural fertilizer with low nitrogen and therefore suitable for fertilizing geraniums (pelargoniums).

what is the approx. dilation rate for liquid comfrey or nettles per gallon of water please.