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Comfrey to the Garden Rescue

Boost your soil, prevent weeds, and build compost with comfrey.

Interested in gardening without using chemicals? Consider growing a patch of comfrey (Symphytum officinale). This European native and member of the borage family is a great garden helper, acting as a soil conditioner, compost booster, and weed barrier all-in-one. Historically, comfrey was considered a valuable medicinal plant, although it is now known that it has carcinogenic properties and should never be taken internally.

A hardy perennial to Zone 4, comfrey is an extremely adaptable plant, and will thrive in nearly any type of soil.  Although extremely drought tolerant, comfrey will perform best in moist, fertile soil.  A full sun to part shade location is ideal.  Comfrey is seldom bothered by pests or diseases.

Comfrey can quickly reach a height of 5 feet, with an equal spread, with multiple stems and fuzzy dark green leaves.  (There are also variegated cultivars:  ‘Variegatum’ and ‘Goldsmith’). Clusters of small tubular flowers may range in color from violet blue, pink or pale yellow, depending on the variety.  As with borage, comfrey’s flowers are especially attractive to bees. Comfrey is usually propagated via root or crown cuttings; most gardeners will grow varieties that do not set seed.

Comfrey leaves are chockfull of the essential plant macronutrients potassium and nitrogen, as well as micronutrients such as magnesium, calcium and iron.  Harvest the leaves at the height of the growing season and allow them to wilt before shredding them.  (Always wear gloves when handling comfrey, as the leaves can cause contact dermatitis).  Use shredded leaves as mulch at the base of nutrient deficient plants or crops that are heavy feeders.  If you would rather use a liquid fertilizer, you can make comfrey “tea” by steeping leaves in water.  The resulting liquid has an undesirable strong odor, but is extremely effective at replenishing nutrients —especially potassium – in plants.

Comfrey is considered a dynamic accumulator:  it has a long taproot, and is able to take up nutrients from deep in the soil. Because of this, comfrey leaves make an excellent green manure.  Just dig chopped leaves into the soil in late autumn and let them do their good work at replenishing soil nutrients.  (This is an especially good way to prepare a vegetable bed for the following year).  The taproot also acts as a clay breaker, penetrating compacted, heavy soils to increase drainage and lessen the chances of nutrient leaching from rainwater and other erosion.

If your compost isn’t breaking down quickly enough, you can try mixing nitrogen-rich comfrey leaves into your compost bin as an accelerator.  Make sure you turn the compost pile after adding comfrey, thoroughly combining the contents for best results.

Finally, comfrey can be utilized as a live weed barrier. Comfrey is particularly effective at controlling rhizomatous grasses.  Plant a row of a sterile comfrey variety alongside crops that you want to protect from encroachment by weeds. Comfrey can also serve as a trap crop, luring slugs and snails away from food or ornamental plants.

If you are considering comfrey for your garden, keep in mind that it has a reputation for aggressive behavior.  While you can obtain sterile cultivars such as ‘Bocking 14’ that do not set seed, it is best to plant comfrey in an area where it will not choke out other plants with its readily spreading root system.

For many gardeners, the benefits of growing comfrey far outweigh any problems, and it is welcomed as a valuable asset to the garden.

Sheryl Normandeau, BA, is a Master Gardener and writer from Calgary, Alberta, Canada. Her articles and short stories have appeared in several international publications. She is the co-author (with Janet Melrose) of the Guides for the Prairie Gardener series.

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I have grown and used comfrey for years to make a poultice for sprains and sore muscles. It works amazingly well and I never got any contact dermatitis. I wouldn’t eat it though.

Leslie Edwards Humez

And the other thing one must be careful about is ignoring scientific findings and replacing medicine with mumbo jumbo. If horses won’t eat it and it’s known to cause liver damage, be rational and give it a miss.

Dolores Williams

When I lived in Northern CA I grew comfrey. I had horses but they left it alone. The rest of my animals and I did have a variety ignored the plant. I wish I had some now to plant. I made tea out of the leaves this was 30+ years ago. I am celebrating my 80th year so I guess it depends on how you look at life and above all use common sense.

Cathy R

My goats have eaten it and, let me look, yep, they are all still just fine. It is more of a treat than a dietary staple though. I have even handled it without gloves and am fine. It has fuzzy, bristly prickles that are less annoying than the ground raspberries, but might bother some folks.
I think that this plant goes into the same category as foxglove (digitalis), use cautiously. Know your plants and what they are capable of. Protect them from indiscriminate grazing by your animals, and it should be fine.
It has been useful as a poultice and now I know other uses for it in the garden if I have more than I need. The bees really like it, and it fills in a trouble spot in our garden. A win for everyone.


Well, for goodness sake!! Did you know that dill pickles are poisonous, too?? Well, everyone in 1902 who ate even one, is now dead! Seriously, ANYthing taken to an extreme can kill you. So, do be careful about ingesting too much clover!!


After readying all post I think il leave this plant alone


Comfrey has so many fantastic benefits. Over 30 years ago I suffered from Tuberculosis and living in GA for some reason the dr’s didn’t catch it, just thinking it was asthma. With no medical relief I resorted to comfrey root which was sold back then and made my own large capsules of which I took 40 a day, you read correctly. It was the only thing that gave me the relief I needed. I was literally on my deathbed with five kids under 8 and hubby working an insane number of hours. There was no way I was doing this alone, so with prayer and herbs we conquered it. Upon moving to AZ a year later I needed a chest x-ray and the technician asked me how long ago I had had TB. Of course I denied it but he said that the x-ray didn’t lie and the scar tissue was the evidence. It did take me years to get back on my feet. At an osteopath’s office in WA state a few years later, once she felt my liver she told me to go straight to the ER because my liver was on fire. I thanked her and went home and started on a liver/gallblader combo suggested by Dr Christopher who in his book had suggested comfrey root for the TB. I now have a huge garden with lots of comfrey, we use comfrey leaves in smoothies (only a couple) and for many bone, flesh and cartilage ailments. It is truly a blessing for anyone with a family and when people throw such a scare on a tremendous gift from God it is very disturbing. I fertilize plants, throw the leaves in the compost and keep it contained to a certain corner area by constantly sharing the plant and it’s awesome uses with others. Eating good healthy veggies and fruits can curtail many a cancer but I literally would have died without comfrey root many years ago and the inconvenience of cleaning out a liver was well worth watching the kids grow up.

Cleo Cast

Univ of Maryland web site states comfrey plants can not be sold in US,UK and many
other countries because of toxicity and danger to liver only ointments can be sold in US

Leslie Edwards Humez

The OFA missed the boat on this one. Having grown it, I would recommend against, unless of course, you want a nice toxic Comfrey Garden. It’s certainly hardy as is stated: in fact, it’s so hardy that its impossible to eradicate without resorting to chemicals. It spreads and will tower over and smother adjacent plantings, and take over wide areas of your perennial plantings unless you are very vigilant. Why OFA would recommend planting a carcinogenic plant that you must wear gloves to handle is a mystery to me; its bad qualities offset the good it might do. If you need a soil conditioner that animals and bees can benefit from, for heaven’s sake, plant clover.

Joan Stek

Is comfrey poisonous to animals? We have sheep, goats, dogs, cats, bees and pigs.

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