Comfrey tea in UK greenhouse

[DarrenC]

I was wondering if anyone has tried just using comfrey tea as fertiliser and what sort of results they got.

It's my first season growing anything and decided to try just using comfrey tea after seeing it on BBC's Beechgrove Garden programme - it also helps that there's a few good patches of it nearby

The only thing I've learned so far is that it stinks and I need to wear gloves whilst making/using it because the smell doesn't leave my skin no matter how many times I wash up

[MendozaMark]

Hi Darren,

Sadly there is no greater benefit to using comfrey in any form then any other plant. It is not superior in NPK, trace elements or anything else we seek. I grew and still have 3 comfrey plants that i planned on using as a fertilizer. I even made 2 batches of stinky tea. I did use the tea and anecdotally, didn't see any difference. Just recently, I put the question of comfrey use to the Garden Professors, a highly qualified authority in the world of Horticulture. They said i was wasting my time basically.

Here is a link to the discussion on facebook.

https://www.facebook.com/groups/Gard...4113272051490/

Cheers Mark

[zipcode]

UK sure loves comfrey tea. I see it on uk forums all the time. I've wondered where they get it from, over here it's a pretty rare plant.

[DarrenC]

Thanks for the replies.... I will have to do more reading, obviously

It's quite a common plant near my home, I have 4 plants in my garden as well and most allotments have a patch of it...

We seem to be coming to the end of our summer here, the night time temps are getting dangerously low (4*C last night) I've been using comfrey tea all year, with no other fertiliser - I have nothing to compare it to but my plants seemed to have done ok. Next year I will try a comparison and grow 3 plants, unfertilised, comfrey and a normal chemical fertiliser (if I can find the space in my greenhouse)

I would say that I'm not dismissing the advice but there's a gardening programme on TV here called Beechgrove Garden and they did exactly that comparison last year and the comfrey plant was the most productive. This also might explain why it's all over UK gardening forums

[MendozaMark]

Originally Posted by DarrenC

Thanks for the replies.... I will have to do more reading, obviously

It's quite a common plant near my home, I have 4 plants in my garden as well and most allotments have a patch of it...

We seem to be coming to the end of our summer here, the night time temps are getting dangerously low (4*C last night) I've been using comfrey tea all year, with no other fertiliser - I have nothing to compare it to but my plants seemed to have done ok. Next year I will try a comparison and grow 3 plants, unfertilised, comfrey and a normal chemical fertiliser (if I can find the space in my greenhouse)

I would say that I'm not dismissing the advice but there's a gardening programme on TV here called Beechgrove Garden and they did exactly that comparison last year and the comfrey plant was the most productive. This also might explain why it's all over UK gardening forums

Please keep us informed on your experiment. I still have lots of tea made so I may do the same on a couple of plants. How are you incorporating it into your watering/feeding regiment ? I was diluting it with water at 1 part tea/20 water ratio, and using it about every 2 weeks mid season on. I couldn't start any earlier because i was starting the comfrey from seed. Also it was just for container growing of tomatoes and peppers.

I got inspired from reading about a master hot pepper grower in the UK using it. So I will blame you Uk'ers if it doesn't work !

Cheers,

Mark

[bower]

Sometimes I forget that gardening is a bit of a competitive sport. Especially when it comes to the best fertilizer, or 'organic' vs 'conventional/chemical' methods... the more competitive sorts do love to trash what others do, whether they have evidence or not.

I remember reading that comfrey was high in potassium in my (very old) copy of the Encyclopedia of Organic Gardening. Just googled and, at the least, this article by Rodale cites some actual analytic test results of what actually is in comfrey.
http://www.rodalesorganiclife.com/garden/comfrey-power

"Researchers in British Columbia analyzed the NPK (nitrogen, phosphorus, and potassium) ratio of comfrey leaves by air-drying them and analyzing the powdered leaf tissues. They found that the leaves have an impressive proportion of 1.8-0.5-5.3. To compare, kelp meal has an NPK ratio of 1.0-0.5-2.5, and homemade compost ranges from 0.5-0.5-0.5 to 4-4-4 (depending on what ingredients you use). Comfrey is also rich in calcium and many other valuable plant nutrients it mines from deep in the subsoil."

I've been using crushed kelp as a source of potassium, but I got a reminder this year, that kelp won't break down quickly at all in cold soil, and left the plants deficient in the bad weather. I'd be better off using comfrey, since it should break down much more easily. I still have some comfrey in the garden in spite of my efforts to remove it a few years ago. Guess I should take care of it and make a thriving patch... I guess you'd need quite a lot to make up by weight the amount of kelp I drag home from the beach every year. Why do I never find the usefulness of something unless I threw it away.

[MendozaMark]

Originally Posted by bower

Sometimes I forget that gardening is a bit of a competitive sport. Especially when it comes to the best fertilizer, or 'organic' vs 'conventional/chemical' methods... the more competitive sorts do love to trash what others do, whether they have evidence or not.

I remember reading that comfrey was high in potassium in my (very old) copy of the Encyclopedia of Organic Gardening. Just googled and, at the least, this article by Rodale cites some actual analytic test results of what actually is in comfrey.
http://www.rodalesorganiclife.com/garden/comfrey-power

"Researchers in British Columbia analyzed the NPK (nitrogen, phosphorus, and potassium) ratio of comfrey leaves by air-drying them and analyzing the powdered leaf tissues. They found that the leaves have an impressive proportion of 1.8-0.5-5.3. To compare, kelp meal has an NPK ratio of 1.0-0.5-2.5, and homemade compost ranges from 0.5-0.5-0.5 to 4-4-4 (depending on what ingredients you use). Comfrey is also rich in calcium and many other valuable plant nutrients it mines from deep in the subsoil."

I've been using crushed kelp as a source of potassium, but I got a reminder this year, that kelp won't break down quickly at all in cold soil, and left the plants deficient in the bad weather. I'd be better off using comfrey, since it should break down much more easily. I still have some comfrey in the garden in spite of my efforts to remove it a few years ago. Guess I should take care of it and make a thriving patch... I guess you'd need quite a lot to make up by weight the amount of kelp I drag home from the beach every year. Why do I never find the usefulness of something unless I threw it away.

I read that info before and that is why i started the comfrey after i was inspired by the UK pepper grower. Unfortunately, the data/research isn't supported by the scientific community. When i have more time I will try to go through the garden Professors threads to see exactly why. I would love to see comfrey prove its worth in the garden as I put a lot of effort into getting the seed here. Like I said earlier, i will trial it out better this year.

I have only used Kelp meal once , threw a few cheap bags on my neglected lawn back in Moncton, NB. You could see where i ran out in terms of lushness and health. I also really liked marine compost, except if the shells were not composted enough. Cut my hand a few times with one batch. No kelp meal or marine compost here in Mendoza .

Could you use the kelp as a top dressing instead ? Maybe it would benefit you in the long run but not cause any deficiencies in the short run. Or just compost the heck of it for a few years before you use it. Free kelp would be hard to turn down.

Cheers,

Mark

[bower]

Originally Posted by MendozaMark

I read that info before and that is why i started the comfrey after i was inspired by the UK pepper grower. Unfortunately, the data/research isn't supported by the scientific community. When i have more time I will try to go through the garden Professors threads to see exactly why. I would love to see comfrey prove its worth in the garden as I put a lot of effort into getting the seed here. Like I said earlier, i will trial it out better this year.

I have only used Kelp meal once , threw a few cheap bags on my neglected lawn back in Moncton, NB. You could see where i ran out in terms of lushness and health. I also really liked marine compost, except if the shells were not composted enough. Cut my hand a few times with one batch. No kelp meal or marine compost here in Mendoza .

Could you use the kelp as a top dressing instead ? Maybe it would benefit you in the long run but not cause any deficiencies in the short run. Or just compost the heck of it for a few years before you use it. Free kelp would be hard to turn down.

Cheers,

Mark

Heh, no fear of me not using the kelp, six ways from Sunday. I love the stuff and as you rightly said it's free.. and a great excuse to go to the beach. I do use it in compost, and it makes the best mulch for my garlic.. no weeds and whatever breaks down they seem to love it. I also let some kelp rot down for a year in a bag, from time to time, after which it is stored as a powder, more or less water soluble goodies for various TLC purposes.

About the 'professors', are you sure they're not turning up their noses on principle and without good reasons? It wouldn't be the first time that I heard scientists scoff just because they heard some other authority say so, and took it on 'authority' alone and/or out of context, without basing their claim on any actual data.
My best guess is that 'comfrey tea' in the recommended dilution etc was not found to have an amount of nutrients equivalent to some other liquid fertilizer ie strong enough to have effects. Just as the 'kelp extracts' which are sold for mucho dinero are used so dilute that they have only a hormonal effect but no significant or measurable nutrient contribution. That doesn't mean there's no potassium value in bulk raw kelp, obviously.

I think a dry comfrey leaf probably doesn't weigh much and it would take a lot of em to make a pound of 'comfrey ferts', with the label value of NPK that was found in that legitimate study, quoted by Rodale. Weak tea is a whole other matter, of course it won't have the same value if it's mostly water. I think I'd be tempted to try the other method described in the Rodale article, just weighting down the raw leaves and letting the rotted liquid drain into a bucket below, then bottle and dilute for use as we do with eg fish emulsion to keep from burning the plants. The liquid product before dilution should have a nutrient value close to or equal the measured value for dried leaves in the study.... and it's not bad, it's certainly comparable to the values listed on my fish e bottle or my dry chicken manure stuff. Which are not free, like a heap of otherwise useless comfrey would be free. For the labour of making it.

If the actually measured NPK value of raw comfrey material is disputed by the 'professors' on scientific grounds, I'd be interested to hear about that. I haven't seen or reviewed the methods used in the cited study, I'm taking on faith that the science was properly done.

[DarrenC]

Originally Posted by MendozaMark

Please keep us informed on your experiment. I still have lots of tea made so I may do the same on a couple of plants. How are you incorporating it into your watering/feeding regiment ? I was diluting it with water at 1 part tea/20 water ratio, and using it about every 2 weeks mid season on. I couldn't start any earlier because i was starting the comfrey from seed. Also it was just for container growing of tomatoes and peppers.

I got inspired from reading about a master hot pepper grower in the UK using it. So I will blame you Uk'ers if it doesn't work !

Cheers,

Mark

Background...
I got a 20l bucket with lid, cut the comfrey and left it for a day to wilt then squeezed as much as possible into the bucket, topped with water and then sealed it up in my greenhouse for 4 weeks. From that point on I wear rubber gloves and old clothes whenever I used it.

It gave me a dirty water look stuff that I diluted 1:10 or thereabouts with water I used this once a week
I've grown all my plants in 13l (about 4 gallon US) containers - because thats what I had...
I started feeding them 6 weeks after their final potting on
The only problems I've had are the weather has been terrible and all my San Marzano's got BER - apart from that I think it's worked for me, just don't know if it'd be better or worse without it - but I have a real phobia of eating stuff chemically treated/fed which is one of the main reasons I started growing anything
I've had quite a lot of cherry toms and a fair few big toms, the biggest a beefmaster at 850g or 1lb 13oz.... Tasty 😁

[bower]

Originally Posted by DarrenC

Background...
I got a 20l bucket with lid, cut the comfrey and left it for a day to wilt then squeezed as much as possible into the bucket, topped with water and then sealed it up in my greenhouse for 4 weeks. From that point on I wear rubber gloves and old clothes whenever I used it.

It gave me a dirty water look stuff that I diluted 1:10 or thereabouts with water I used this once a week
I've grown all my plants in 13l (about 4 gallon US) containers - because thats what I had...
I started feeding them 6 weeks after their final potting on
The only problems I've had are the weather has been terrible and all my San Marzano's got BER - apart from that I think it's worked for me, just don't know if it'd be better or worse without it - but I have a real phobia of eating stuff chemically treated/fed which is one of the main reasons I started growing anything
I've had quite a lot of cherry toms and a fair few big toms, the biggest a beefmaster at 850g or 1lb 13oz.... Tasty 😁

Darren, it sounds like you got a great yield for small containers and terrible weather. And no ferts but the comfrey - it's great. You're obviously doing something right - I think regular feeding for plants in containers is the way to go, and maybe weekly is better than every two. I have a tendency to forget when I fed last, until I notice they stopped growing.
I couldn't see the picture. 1 lb 13 oz is huge!

[DarrenC]

Originally Posted by bower

Darren, it sounds like you got a great yield for small containers and terrible weather. And no ferts but the comfrey - it's great. You're obviously doing something right - I think regular feeding for plants in containers is the way to go, and maybe weekly is better than every two. I have a tendency to forget when I fed last, until I notice they stopped growing.
I couldn't see the picture. 1 lb 13 oz is huge!

There wasn't a picture.... I inserted a smilie thing on my iPad, rookie mistake

I found weekly feeding easy to remember, being in containers in a greenhouse meant I had to water them everyday anyway

Hopefully next year the weather will be more cooperative, I had 2 ARGG plants that have given me 4 ripe tomatoes, they have another 30 up ripe ones but I think it's just been too cool this year. The Cherry/Sungold plants are still going strong though

[Lindalana]

I belong to a different group of gardeners who believe that soil already has all NPK plant needs and as long as soil has biology able to mine it out and deliver to plants all is kosher. So all this NPK talk goes out of the window with my way of thinking. And that is where compost teas and compost extracts to be precise come in as well as kelp/ comfrey teas.
Thing is with my foliar application of 1 tsp of kelp per 1000 sq ft I am not providing NPK, but like with well prepared dishes I am adding that pinch of salt that changes bland dish to delight.

[Labradors2]

Several years ago, I bought a comfrey plant at my local Horticultural Society's plant sale. The person who provided it said that it's a compost accelerator so I planted mine beside my two composters and I throw in some large leaves every now and again, especially when the plant gets over-grown, and when I cut it down in the fall. The pretty blue flowers are attractive to bees.

Although I've been tempted to make comfrey tea, having water sitting around to encourage the mosquitoes never sounded very appealing, but maybe I'll give it a try next year.

Linda

[bower]

It was so cold here this year, July was colder than a normal September and broke the record. My plants really suffered with potassium deficiency - as I learned, they can't take up K in cold soils, and the fruit quality really suffered for nearly all the large ones. Grey wall, uneven ripening, etc.

I probably could have remediated the situation by warm watering with some nice teas, comfrey looks good to me as a source of warm liquid bits of potassium, instead of making it worse by pouring icy cold well water on them. I will do it next time we have a cold one, this time I didn't know there was/would be such a problem until the larger ones started to ripen.

All the teas I've tried for plants have been great. I like to make Spirea tea for the salycilates - Just throw it in a big kettle, boil up, steep, and serve with water. This stuff doesn't smell bad and it kept in a bottle for ages - months for sure with no bad smell or sign of rot. The plants really loved it. I wonder if comfrey could be prepared the same way..
Actually my mom has a few big patches of comfrey out in her field. I've seen them after the frost gets them and in the spring, all brown and crispy and covering a fair patch - if we get some dry weather I'll look for that in the fall, maybe try storing it as a powder and use like my decomposed kelp stuff.

[maf]

I looked through the "debunking" of comfrey in the facebook posts and it all seems to entirely miss the point of growing this plant which is that its very deep roots will draw minerals from deep within the soil where they would be unavailable to most other plants. This obviously allows the recycling of nutrients that would otherwise be lost for good.

Add to this that it is a very good source of trace minerals, is easy to break down in the compost heap or as a liquid or if applied directly to the soil as a mulch, and you have a very useful resource that is essentially free apart from the space needed to grow it.



(I should add that I don't currently use comfrey, as I don't garden on a large enough scale to make it worthwhile to devote some of my growing space to it.)