My recent Comfrey Research

Settle in good people, this may be longwinded. I tend to run that way in this sort of setting!

To preface my recent research findings, let me share that I am self-taught in most things, and my interest in herbal health alternatives came to me at about age 20. I read a couple books on my mother's shelves by Jeanne Rose and caught the bug! I've been enthralled since by comfrey as one of my most used herbs for healing.

With the advent of realizing my dream of land, animals, gardening, growing my own herbs in greater variety and amounts etc, I am revisiting comfrey for all the additional benefits of this favored plant. Everywhere that you learn more about permaculture, comfrey comes up. I've learned new terms for the uses of comfrey like bioaccumulator! (Gosh I love the $32k words!)  But after my extensive search for input here on permies, I was still missing the knowledge that I really wanted. Which comfrey was best for feeding to the critters? Was it different from the one I'd want to use in my Rx garden? Might I need to court the devil and have a patch of common comfrey (symphytum officinalis) close to the house so I could stay on top of preventing seeds and still have it for my uses?

In my search here, some posts that lead me further down the rabbit hole are these:
https://permies.com/t/175487/determine-Bocking-Bocking-Comfrey  
https://permies.com/t/15975/Comfrey-Bocking-Clarification
Carol Lex had it right here  https://permies.com/t/15627/Comfrey-Varieties
One post did direct me to acquire the out-of-print publications by Lawrence D. Hills. After some trouble with the requests not working at that site (found here  https://soilandhealth.org/search-by-author/?wpv_view_count=258&wpv-wpcf-originalauthor=Hills%2C+Lawrence+D&wpv_filter_submit=Search  ) I got them downloaded and began reading.

There is also S. uplandicum (the Bocking varieties), S. asperrimum (prickly comfrey), S. peregrinum that was the subject of much of the publication "Russian Comfrey", S. tuberosum (tuberous comfrey) that has twice the chromosomes (72) and is declared unpalatable, S. uliginosum, and something called "Hidcote Blue" that has invasive roots.  Who knew there were so many Symphytums!?

Using comfrey to create biomass, whether to feed your animals, feed your plants, or build soil, it will need to be cut several times each growing season. To cut it down to 3 inches tall 5 times is not unreasonable. One set of records kept by a farmer show a first cutting to see 5-8 pounds Per Plant, 12-15 pounds Per Plant for the 2nd and 3rd cutting, dwindling to 8-10 pounds per plant in the 4th cutting and a mere 3 pounds per plant at the 5th cutting. There is some very valuable information right there!! I've already secured nearly 60 plants of comfrey for the property!

I created 3 pages of notes, 1 page per comfrey that I know is out there and easy enough to find and obtain. I wanted to know more about true common comfrey, Bocking 4 and Bocking 14.

I had first secured Bocking 14 root cuttings at riseandshinerabbitry.com . My notes read as follows: extremely robust and vigorous / has a slightly higher allantoin content (the medicine in the plant) / shallower roots / primarily garden fertilizer as tea, in compost, as chop and drop / used interchangeably with Bocking 4, NPK of 1.8/0.5/5.3  / dynamic accumulator of iron, silicon, nitrogen, potassium, calcium, magnesium and trace minerals / earliest and best for most useful job in the garden.  An allantoin analysis comparing 4 of the Bocking varieties shows B(ocking) 2 has 0.23%, B4 has 0.34%, B14 has 0.44%, B17 has 0.23 %. With a final note quoting Mr. Hills, "Bocking 14 found most effective in banishing scour risk from foals & racehorses. It heals the digestive irritation, passing through if there is nothing to heal." Then mentioning that calves and pigs also gain benefit.

About common comfrey I have gleaned that it WILL self-seed, is not as vigorous as the B14, & has less of the toxic pyrrolizidine alkaloids which are hard on livers. Since it seems both publications were focused more on the Russian Bocking varieties, and both S. asperrimum and S. peregrinum from studies done over 100 years ago, not much attention was given to the common form.

The B4 has deeper roots than the B14, contains more protein and slightly less allantoin (by 1 tenth of a percent! and so could be used interchangeably with B14), with a wider leaf than B14 and thick stems like S. officinalis, it is the preferred comfrey for food in both poultry and humans. Mentioned was Bocking 7 as being the "best tasting" for humans and that Bocking 4 is nearly as tasty AND has higher yields! I've secured an entire small box full of these root cuttings as well, in trade for some seeds I had. Thank you Trace Oswald! L.D. Hills does say that this one IS self-seeding, but that the way the flower is made mostly prevents pollination.

Something I don't think I fully understood about comfrey until reading the above-mentioned tomes is that each plant can get SO very large. 15 pounds for a single plant seems like a really big plant! I've only ever ordered dried leaf and dried and cut root by the ounce or pound and never seen it growing.

In feeding this plant to your livestock, it is recommended to allow 24 hours of "wilt" time.

Since I am currently roughly 2000 miles from the place where these are getting planted at this time, I can not really address any experience with the varieties chosen. For now my plan is to use the B4 around the orchard trees (to ultimately be a food forest orchard) due to the deeper roots, to chop and drop around the entire area, or use as supplemental animal feed. I will likely use the B14 as a tea to feed the plants, in compost piles and as a green in hugelkultur beds, and of course in the ointments I make. I also think that in order to know which variety I'm looking at, keeping one on one side of the road, and the other on the other will help until I (we) can ID them on sight. (This property sits astride a hill/mountain with something of a road running through it, and my daughter and her family will be on the east side while my husband and I domicile on the west side of the road!)

I have some experience of growing these. In the right condition they can be amazing, but contrary to what I have seen in some people say, they can also be a bit fickle.

They have an excellent root system and feed the soil under the drip line. The root zone of a comfrey if you dig into it tends to be dark, rich and moist. BUT they only really thrive when they have those conditions. I have found that planting them in drier spots with poorer soils yield poor results. They need a reasonable amount of moisture retention and soil nutrients, at least to get started.

My comfrey is doing best in slightly shaded spots, and where soil has been previously amended around the vegetable patch. I have a bunch of plants on the outside of the rabbit proof fence that are doing really well after just one year. In another spot they are barely hanging on after 5 years.

At a different property, I planted one comfrey plant near an apple tree. At that site there is abundant soil moisture and nutrients, and that plant is an absolute thug. It grows vigorously each year, and does a superb job of protecting the apple from encroaching grasses. We get a huge amount of material from it each time it is cut. One plant easily fills a wheelbarrow. The difference in vigour is remarkable, especially as they are the same variety from the same original root stock.

I see their greatest value as being around fruit trees, where they shade the soil and prevent grasses and other weeds from competing with the trees. This works especially well with a ring of comfrey that is well established on all sides of the tree.

^^ agree about fickleness, I've tried to grow it several times and only this year am I getting anywhere. I also have it under trees (orange, mulberry, and guava).
I don't know what kind I have, as it is just sold here as comfrey. But the fertilizer tea is FABULOUS, and the rabbits enjoy eating it. And yes, once they're established these plants put out a lot of leaves!

I'm glad you are happy with our trade Cindy.  If you cut the pieces I sent into smaller ones at planting time, if you haven't planted them already, you will easily get 100 plants from those roots.  Let me know how they do for you.  I love hearing progress reports.