Which variety of comfrey to grow?


The Living Force
I am planning to grow some comfrey at home, and it seems like the Bocking No.14 hybrid is ideal - the highest amounts of alantoin, and it is not as invasive as other varieties, being sterile. It may also have lower levels of the alkaloids, although this is not a great concern for me, as I'll probably use it for composting most of the time. I'm wondering if there's any reason to choose another variety, though. Since we have a small yard, having this stuff seed everywhere and spread could be a problem, although it could be useful in the back yard where there is a bunch of sand remaining from the previous owners' pool - maybe the comfrey's tap root could help rebuild the soil by pulling nutrients up and then being used as mulch/compost?

So I guess what I'm wondering is: are there any specific concerns about using a hybrid for medicinal use?

This website seems to address most of my questions:

Traits of All Russian Comfrey Cultivars

All types of Russian Comfrey (cultivars Bocking No. 1 through Bocking No. 21) are botanically known as "Symphytum × uplandicum" or "Symphytum x uplandica". They all are a cross (natural hybrid, not GMO) between rough comfrey and common comfrey. They grow to 4 feet tall including the flower stalk.

Russian comfrey has purple, magenta-pink, red or blue (that fade to pink) flowers. The seeds are not viable (will not grow). It has to be reproduced by root and crown cuttings.

Russian Comfrey is very hardy. It can withstand temperatures as low as -15 degrees. Good in USDA Zones 3-9.

The powerful roots of Russian Comfrey Bocking #4 go down 6-8 feet. Bocking #14 roots go down 8-10 feet. Both are good plants to use to break up hard soil.

High in Protein and Biomass

Both Russian Comfreys produce up to 100-120 tons per acre of leaf biomass (recently cut) per year. This is about 12.4 tons of dried comfrey leaf per acre. This is 3 times the amount that True Comfrey produces. Alfalfa yields 18 tons per acre (just cut). Corn is 25 tons per acre before it is dried. Pasture grass is 25 tons an acre.

The protein amount in dried comfrey is 20-30%. Most beans (legumes) are around 8-9%. Soybeans are around 17%.

All comfrey (Russian and True) contains Pyrrolizidine Alkaloids (PAs) and can be toxic if used internally by people. It is hard on your liver. Small young leaves have higher concentrations than larger, older leaves. The PAs in roots are concentrated more in small young roots. Roots contain more than leaves. Leaves have about 0.06% alkaloids. Roots have about 0.2-0.4%.

Bocking #4 and #14 Are Similar

Both Bocking #4 and #14 can be used as garden fertilizer, compost activator, mulch, or be fed to animals as fodder. Both reduce transplant shock of plants.

Bocking #14 is more frequently used as a garden fertilizer. Bocking #4 is used more as an animal fodder. It is usually preferred by animals over Bocking #14. Either variety can fulfill your needs if you only want to grow one type.

Comfrey has been grown and used as an healing herb since 400 BC. True comfrey (Symphytum officinale) is usually suggested as the best one to use internally medicinally though caution is advised. Never use a lot of it internally.

There are studies that seem to indicate that Russian Comfrey has fewer of the toxic alkaloids than True Comfrey. Externally all comfrey (True or Russian) is good to use. Contact your doctor or herbalist.

Bocking No. 14 and Your Garden

Bocking #14 is the preferred type when used as a garden fertilizer.

Leaves are wilted and then placed in a hole or trench to act as nutrition for whatever is planted in the hole such as potatoes. It's stems are smaller and thinner than Bocking #4. So they wilt easily and are not likely to start sprouting into a comfrey plant when covered with dirt.

Another way to use it is by making liquid fertilizer or compost tea. You put about 5 pounds of comfrey leaves in 7 gallons of water. If you want a lot of fertilizer, use a 55 gallon barrel. Use a proportional amount of leaves. Cover with a lid and let sit for 4-6 weeks. The liquid is used to fertilize your plants.

The Book: "Comfrey Report"

From the book "Comfrey Report: The Story of the World's Fastest Protein Builder and Herbal Healer" by Lawrence D. Hills:

"There are two commercial strains-- the Webster and Stephenson. Bocking No. 14- This is the dominant in the Stephenson strain, 80% to 90%. The flower stems are slender and frequent and are entirely wingless. The flowers are Imperial Purple 33/3 fading to Lilac Purple 031/3. The leaves are pointed, slightly serrated at the edges and vary in proportion from 5 to 12 and 3 to 6."

The photo to the left is Lawrence Hills who wrote several comfrey books that are the authoritative works on the subject. He is the person who created the natural hybrid Russian Comfrey, Bocking #1-#21. He is next to a comfrey plant.

Comparing Bocking #14 to #4

Allantoin is the healing chemical found in all comfrey. It stimulates cell growth and repair. It has been used by herbalists for 2000 years. It is used in skin care products. It is found in the roots and in the leaves.

In Bocking #14 leaves allantoin is 0.44%. In Bocking #4 leaves it is 0.34%. In True Comfrey (S. Officinale) it is 0.30%. Allantoin heals digestive problems so comfrey leaves have been used for decades to reduce scouring (diarrhea) in horses, cows and pigs.

Russian Comfrey is high in potash (potassium). Leaves of Bocking #14 are 7.09% potash. Bocking #4 is 5.04%. True Comfrey (Symphytum officinale) has 5.3% potash. Wilted comfrey has more than twice as much potash as farm manure and 30% more than compost. The Nitrogen-Phosphorus-Potassium (NPK) ratio of True Comfrey is 1.80-0.50-5.30.

More Bocking Comparisons

All comfrey contains vitamin B12, one of the few plants to have it. Most vitamin B12 is found in animal products such as liver, eggs and milk. Leaves of Bocking #14 have 4.4 nanograms of B12 per gram. Bocking #4 has 11.6 per gram (more than double #4). Dried yeast has 1.1 per gram.

Bocking #14 Comfrey is more rust resistant.

Bocking #4 is more drought resistant than #14 because it has deeper roots.

I just ordered 2 root cuttings of Bocking No. 14 from the above website, as it seemed to be a good value and comes with a comfrey growing guide. I could get another variety eventually if there's a need.


I don't have any additional information on the Bocking varieties than you found, but I also ordered a couple of rootlets from Nantahala and planted them last fall. I planted one #4 and one #14 and they have already sprouted up this spring and look very healthy. I'm excited to see how my pigs and poultry like the #4 when it is mature enough to harvest leaves from. I plan to use the #14 mainly for a compost addition.

I have one of Lawrence Donegan Hills books "Comfrey: Fodder, Food & Remedy" on my wish list. With him being the creator of the Bocking varieties it should be some very interesting reading. The nice thing about the Bocking varieties is that they will not spread from seed and when they grow larger the plant can be divided and transplanted.

Here is a little more livestock specific information regarding Comfrey.

Two extremely useful plants I recommend to all homesteaders are comfrey and stinging nettle . In addition to myriad food (for both humans and plants), medicinal, and soil-building uses, both plants are excellent feed for poultry. Comfrey is amazingly productive, especially if fertilized heavily (and it will take any form of fertility you throw at it, including raw chicken manure). Protein content is high (higher than alfalfa, and can if well grown be as high as soybean, dry weight basis). I cut and feed as needed, more at times in the season when the pasture is less generous. Chickens eat comfrey well. Geese love it.

I am in the process of greatly expanding my comfrey plantings. (It is an extraordinarily easy plant to propagate.) The next big “wave” of propagation will feature planting comfrey patches out on the pasture, where the birds will “graze” the comfrey themselves. I plan to keep the plantings tight, dense, and relatively small. They are incredibly tough plants, but if they seem to be suffering from over-grazing by the birds, I can protect the patches with temporary fencing.

Both comfrey and stinging nettle can be dried and fed as “hay.” My experiments with both have been challenging thus far—they are much more fragile than a grass hay. My next attempts with both will feature thorough drying, then stuffing into large burlap bags, in which the shattering into leaf meal will not be a problem. I will experiment with feeding straight, and with adding to ground feeds.

It should be added that in recent years there has been some “scare talk” from official quarters about pyrrolizidine alkoloids found in comfrey. The alkoloids are indeed present, and are indeed toxic to the liver in massive, pure doses. However, my conclusion from research I have done is that there is no toxicity problem, acute or chronic, associated with consumption of whole comfrey, by either humans or livestock. (See Comfrey Report , by Lawrence D. Hills.) Whenever I slaughter fowl, I practice a form of divination I call “reading the livers.” As long as the livers of birds who have been eating comfrey remain healthy and free of abcesses, I will have no concerns about feeding comfrey.


The Living Force
Russian Comfrey is very hardy. It can withstand temperatures as low as -15 degrees. Good in USDA Zones 3-9.

I take it this is in Farenheight? I am also thinking of growing comfrey for my pigs. And now i realize it will be good for the fowl i plan on having. I found a place to get all types of fowl chicks. The strange thing is that the live chicks come in the mail. It seems to be successful though.


The Living Force
davey72 said:
Russian Comfrey is very hardy. It can withstand temperatures as low as -15 degrees. Good in USDA Zones 3-9.

I take it this is in Farenheight? I am also thinking of growing comfrey for my pigs. And now i realize it will be good for the fowl i plan on having. I found a place to get all types of fowl chicks. The strange thing is that the live chicks come in the mail. It seems to be successful though.
I assume it's Fahrenheit, since it's a U.S. article. Mail-order chicks sound curious indeed - I hope it's not too hard on them.
Top Bottom