The Wonders of Comfrey

As I continue my journey deeper into veganic gardening, I am perpetually amazed at the wealth of resources present in our own backyard. It seems that anyone with a proper compost pile, a source of mulch or green manure, and common beneficial “weeds” scattered about has all the resources needed to help their garden thrive.

One of my new favorite herbs for the garden, or “weeds”, depending on your perspective, is comfrey (Symphytum officinale), which has a wealth of uses for both our own health and the health of the garden.

Comfrey’s deep roots work to bring nutrients up from the subsoil. These nutrients are then made available in the abundant number of leaves it produces every year (4-5 lbs of leaves per established plant per year). The leaves are rich in nitrogen and potassium with a decent amount of phosphorus as well, making them a wonderful homegrown fertilizer. Researchers in British Columbia analyzed the NPK (nitrogen-phosphorus-potassium) ratio of comfrey and discovered that the leaves have a remarkable NPK ratio of 1.80-0.50-5.30.

Next: NPK of animal manures

When we compare these nutrient ratios (1.80-0.50-5.30) to that of animal manure, we can see how far superior comfrey* is.

Dairy Cow: .25-.15-.25
Steer: .70-.30-.40
Horse: .70-.30-.60
Sheep: .70-.30-.90
Chicken: 1.1-.80-.50
Rabbit: 2.4-1.4-.60

From: Rodale’s All-New Encyclopedia of Organic Gardening, An Illustrated Guide to Organic Gardening, by Sunset Publishing, and the Rodale Guide to Composting.

Note: Naturally, nutrient values of animal- or plant-based manure can vary greatly from specimen to specimen.

As you can see from this list, the nitrogen content of comfrey is higher than almost all animal manures found on the market today and its potassium concentration is far superior to all, making it an ideal fertilizer for plants that produce flowers, seeds and fruit for which potassium is an essential component. This, along with the more important ethical and environmental incentives for not using animal inputs in our gardens, makes growing comfrey as a fertilizer a win-win.

If you don’t think the NPK ratio of the dried leaves is impressive enough, you can also make a concentrated liquid fertilizer out of comfrey (see my next post on uses for comfrey in the garden) with an NPK ratio of about 8-2.60-20.50! (You’ll want to dilute this before use.) The leaves are also full of silica, calcium, iron, magnesium and other essential nutrients to help your fruiting plants thrive.

* Air-dried powdered comfrey leaf tissues.

Next: Health Benefits of Comfrey

Health Benefits of Comfrey:

Comfrey is also called knitbone, knitback, consound, blackwort, Ass Ear, Slippery Root, boneset, yalluc (Saxon), gum plant, consolida and bruisewort.

From the pattern of these names, you’ve probably guessed that comfrey can do more than benefit your garden. It also has powerful healing properties, supporting the body’s ability to repair damaged tissue and bones.

Comfrey roots and leaves contain a substance called allantoin, which, along with other beneficial compounds in the plant, supports healthy cell growth and reduces inflammation. Comfrey has been used externally as a poultice or ointment to heal bruises, broken bones, closed wounds, pulled muscles and ligaments, fractures, as well as reducing inflammation from sprains and more.

There is some controversy over comfrey though, because it also contains poisonous substances called pyrrolizidine alkaloids that have been shown to be toxic to the liver when ingested. For this reason, oral comfrey products have been banned in many countries, including the U.S. It is reported that some of the pyrrolizidine alkaloids can be absorbed through the skin as well, but there are varying opinions as to the actual risk of poisoning through topical use. It is best to find a knowledgeable herbalist or naturopath who can teach you the correct way to use this wonderful herb. Most recommend using comfrey externally, for no more than 10 days at a time and no more than 4-6 weeks out of the year. While many feel that caution with this herb is important, it is also a powerful healing tool if used correctly.

So now that you know all about this wonderful herb, weed, and garden companion, get out there and get growing!*

*Make sure you know more about how comfrey grows before planting it: it is a sturdy plant and will thrive in most soil. Because of these factors, it can be difficult to get rid of if you decide to remove the plant. For more information on this, check out my next post.


Naomi Dreyer
Naomi Dreyer1 years ago

Comfey - it's new for me. Thanks.

Jeanne Rogers
Jeanne R1 years ago

More than I ever knew. TYFS

Joseph E Fasciani

The author cannot read: rabbit manure, at TOTAL nutrients of 4.4% is secoond to comfrey, which has 7.6, certainly in first place, BUT 5.30 of that is Potassium, which isn't so much a fertiliser material as a plant growth regulator. It IS crucial, and not to be discounted, BUT during the growing season most plants require a ratio of 3-1-2 to achieve optimal growth. []

The elements are usually read as N-P-K, and the differences in their availability are understood as a ratio to one another. Lawn grasses, corn, and bamboo all do best when a 3-1-2 ratio fertiliser material is applied, such as 21-7-14. Comfrey, at 1.80-0.50-5.30, has a LOT of K in relation to the first two, as well as trace elemts. I think the high K & the elements are what gives its greatest benefits.

Most plants will require a lot more Nitrogen to truly thrive, especially in adverse situations.

Anna Ballinger
Anna Ballinger4 years ago

Thank you for sharing.

Fred Hoekstra
Fred Hoekstra4 years ago

Thank you Alisa, for Sharing this!

Mar Yannu Hathory

remarkable that the U.S. banned comfrey, due to low potential of liver toxicity ... almost certainly mitigated by using the WHOLE plant, which is how Mother Nature designed it. if the U.S. powers-that-be can turn a condemnatory eye on comfrey, wouldn't you think that Monsanta (shudder) would be under scrutiny? oh, wait. i forgot. we have to bribe our regulatory authorities, and herbalists don't have lobbyists with megabucks. how could i forget that!

greenplanet e.
greenplanet e5 years ago

Super herb.

Abbe A.
Azaima A5 years ago


Mary Mattarelli
Mary Mattarelli5 years ago

I am shocked to read that comfrey can be toxic when eaten. I grew up with my mother cooking it and we all ate it. My mother grew up with her mother cooking it too. when we were kids my mother cooked it for us if we had tummy pains. I havent eaten it for years but my mother who is 81 years old eats it often. My daughters inlaws eat it also and when I told my son inlaw that I read that it can be toxic he said his parents have it growing in their garden and they also eat it.

Howard C.
.5 years ago

Really interesting, thanks for posting