Comfrey: super-plant or overrated weed? Have you ever wondered why useful plants are usually delicate creatures, yet weeds just thrive, without any care at all, and pondered wouldn’t it be wonderful if there was such a thing as a useful weed? Comfrey is it. A perennial herb, a member of the borage family, its deep tap roots mine the soil of nutrients, filling its leaves with minerals such as the holy trinity of plant food, nitrogen, and phosphorous and potassium, along with calcium and iron. It remains only to harvest it and make a comfrey “tea” (concentrate) to use as a plant food, use it as a mulch and even feed it to animals. Comfrey leaves contain more Nitrogen and Potassium/Potash (K) than farmyard manure or garden compost and more Phosphorus than farmyard manure. They have a low fibre content, so they readily decompose, producing comfrey tea and a relatively low carbon to nitrogen ratio so that they don’t rob the soil of nitrogen as they decompose (when laid on the surface or dug in).
If I plant it, will it spread like a weed? That depends on what variety of comfrey you have. Common comfrey Symphytum officinale, seeds freely and therefore may well become a problem. Russian comfrey (Symphytum x uplandicum) on the other hand, produces very little viable seed, so conveniently stays where you put it. But it will always stay where you put it, as you’ll never dig it out without breaking off a little bit of root, which will re-grow, so choose the position of your comfrey patch with care. The Bocking 14 cultivar of Russian Comfrey was developed during the 1950s by Lawrence D Hills, founder of the Henry Doubleday Research Association (now called Garden Organic) and is even richer in the useful minerals. The Bocking 4 cultivar was developed to be more suitable as animal fodder but I can’t source any in the UK or France and have only found Richters in Canada selling it.
How do I grow comfrey? Without seed, we propagate it from root cuttings. Simply plant your root cuttings just below the surface, water them in and wait (you can mulch them with cardboard, as we’ve done here, see photo). One extra tip, use some anti-slug and snail strategies until the plants get up and going, as these gastropods really like comfrey (another of its uses to place cut leaves around plants as a slug barrier, as the slugs will go for the comfrey, in preference). If you’re starting off, I suggest that you buy no more than six plants. You’d be surprised how much leaf material you’ll be able to crop once the plants are established (leave them a year before you start cropping).
They might mine all these nutrients for you but they also appreciate being fed and are greedy for nitrogen when growing; they can cope with fresh (i.e., uncomposted) chicken manure, so we tend to clean our chicken house onto our nearby comfrey patch.
You’ll also then be able to propagate further plants by lifting one and divide the roots into offsets and cuttings (see photo: offsets at the top, cuttings below) and then plant these as you did with your original cuttings, and don’t forget to put one bit back in the hole where you lifted the original plant from.
When and how to cut comfrey? Use ordinary hedge trimming shears and chop it off 5cm (2 inches) above the ground.Think about wearing gloves as the bristles can irritate your skin. Cut in spring, when the plants are around 60 cm (2 feet) high and before flowering stems develop. Once the plant is well established—I’d give the plant a year to settle in before you start harvesting leaves—cut every time the plant reaches 60 cm (2 feet) high and before flowering stems develop and you should get several cuts a season. At the end of summer, stop cutting, letting the plant grow on and build up its strength to see winter through.
How do I make comfrey tea?
Making comfrey tea – liquid concentrate. I think that the video explains all. This photo shows the plastic dustbin full of leaves which reduces to the goo in the video, don’t add water. Dilute to use, 20 water to 1 comfrey juice (by volume) when it’s thick and black or 10:1 if it’s thinner and brown in colour.
Do animals like comfrey? Whether fair or not, the spread of wild comfrey along roadside hedgerows is often attributed to gypsies that fed comfrey leaves to their horses as a tonic. It’s said that Russian comfrey was introduced into Britain specifically as a fodder plant. We’ve got an established comfrey patch. The chickens peck at it en passant, a sort of “Drive-Thru” eatery, and Bunny Lapine scoffs it, so I recently thought I try out our pigs and goats on it. Fellow NotDabbling writer Monica, told me that she planted comfrey some years ago, “but the sheep ate it all before it could get going and I lost it.” So it’s thumbs up from sheep. However, our pigs, who are free range, and so have a wide variety of stuff to snack on, didn’t seem desperately interested and, as for the goat, watch the second video for our scientific taste test and make your own mind up.
Comfrey as medicine? A vernacular English name for comfrey is “knitbone” and medieval herbalists called it “bone set”. It contains a substance called allantoin, which promotes healing in connective tissue. Effective as it is externally, don’t take it internally, as it contains alkaloids, which can cause liver damage in large quantities.
Thanks to the following books for their information: Comfrey for Gardeners published by and available from Garden Organic (Henry Doubleday Research Association); Flora Brittanica by Richard Mabey; The Earth Care Manual: A Permaculture Handbook for Britain and other Temperate Climates by Patrick Whitefield and Wikipedia.