If you have any interest in permaculture or regenerative farming/gardening, chances are you’ve heard many miraculous things about Comfrey. For instance: The deep roots ‘mine’ for nutrients and collect them in the leaves/it’s a biodynamic accumulator! It is a fabulous forage plants for livestock/chickens love it! You can brew a nutrient-dense/though extremely smelly compost tea with it! It can be used to cure cuts and bruises! … and many more. Go ahead, search ‘comfrey permaculture’ on Google and see whatcha get. I’ll wait.
Whenever something has these kinds of inflated claims, I am suspicious. It happens regularly in the gardening world (coffee grounds and eggshells, anyone?). Let's get one thing straight: plants are miraculous, period. Take a carrot seed. It’s unbelievably tiny. Within its microscopic proportions, it has everything it needs to send down roots and produce cotyledon leaves, which provide enough photosynthate to make those huge feathery fronds and develop a long, fat, juicy, orange, delicious tap root. This is simply crazy. Or how about the tomato flower, which is self-pollinating? It has everything it needs, both male and female parts, to produce fruit by itself - it doesn’t need the services of a pollinator. Or the humble bean, which allows a bacteria in the soil to colonize on its roots in order to take nitrogen from the air and provide it to the plant. Or the hormone in all plants called auxin, which is produced in the stem and root tips that cause the elongation of the plant? I mean. You can’t look at plants and not see how miraculous they are, doing things that we didn’t engineer them to do; they’ve simply evolved to do them over millions of years. Comfrey is no different.
Comfrey is in the Borage family, and we’ve already sung the praises of the flowers in this family. They are very attractive to bees (carpenter bees in particular), though I have also noticed hummingbirds love the bell-shaped comfrey flowers too. And they are lovely little inflorescences, in a curled shape called a ‘cyme.’ A cyme is a curved stalk of flowers; the terminal bud flowers first, and the others further down and underneath flower afterwards. The leaves are winged, with the wings going down a large part of the petiole, or stem, of the leaf. As you can see, the leaves can get quite large, up to two feet long.
You start comfrey from a root cutting. No special treatment is needed. Just cut some of the root out (which doesn’t hurt the existing plant at all), and bury it. Soon you’ll have a plant. By its second year of life, it’s ready to be ‘harvested,’ if you want to go that route. If not, the plant’s leaves will slowly sort of keel over to the sides, like flowers in a vase, and new leaves will come up from the center. It tends to die back in frost or cold, and re-sprouts reliably every year.
The added benefit of comfrey lies in its ability to be ‘chopped’ down several times a season, and it will come right back. Why would you want to do this? There’s value in the leaves. Like all leaves, comfrey’s have a lot of nutrients in them. After all, that is how trees (and many other plants) fertilize themselves; they drop their leaves to the ground to decompose and provide nutrients over time. Comfrey leaves have a pleasant nutrient ratio of about 3-1-5. That means it’s a pretty good fertilizer. You can add them to your compost, especially if you have a lot of ‘brown’ in your pile like dead leaves or bark; the nitrogen in the leaves will help the compost break down faster (just like grass clippings will). You can feed them to your chickens (apparently they also have a lot of calcium, so that is nice for your egg-producing birds), but they will likely snack on them rather indifferently, not inhale them like they do kale. Comfrey leaves are fuzzy, like borage, and kind of hurt your hands and, I imagine, livestock mouths. You can also use them as a mulch, which is what I did with my latest batch - I put them around a bed of tomatoes.
As for the claim that the deep taproot of comfrey ‘mines’ the soil for minerals: That’s kind of a fallacy. Taproots are generally formed to help anchor the large up-top biomass of the plant. Only really large plants get them, and sometimes not even then. It’s also used as a place to store the sugar and carbohydrate that the plant gains from photosynthesis (that’s what makes carrots so delicious!). Most plants get their water and nutrients from surface roots, which are in the top 3-8 inches of soil, pretty shallow.
And please, for the love of God, do not make the kind of comfrey compost tea everyone suggests on the forums. They tell you to put comfrey leaves in a bucket, weigh them down with a brick, fill the bucket with water, cover it, then let it sit for 3-6 weeks! There’s a reason it smells so bad when you open the bucket, and it’s called anaerobic bacteria! Anything anaerobic is not going to be healthy on your soil or your plants. One reason compost is successful is because it’s aerobic and full of oxygen!
There is some evidence that comfrey is a good plant to have around for bee stings, cuts, inflammation, and muscle soreness. To quote the NCBI: “Comfrey has a centuries-old tradition as a medicinal plant. Today, multiple randomized controlled trials have demonstrated the efficacy and safety of comfrey preparations for the topical treatment of pain, inflammation and swelling of muscles and joints in degenerative arthritis, acute myalgia in the back, sprains, contusions and strains after sports injuries and accidents, also in children aged 3 or 4 and over.” You can see their paper for more information about the clinical trials that have been conducted.
So grow comfrey for its beauty and its value for pollinators, and use it for mulch or compost if you feel so inclined. It can’t hurt to have it around for topical pain relief or to ease swelling. And it is a great plant to put under fruit trees and in neglected parts of your garden. It will spread easily, so be warned that if you dig it up and cut the roots, you could have plants everywhere (and it reseeds - another particularly borage-like trait). But it’s a pretty plant, so that might not be a bad thing!