Comfrey is a plant with a multitude of uses not only in the home apothecary but also in the garden. There are several species in the genus Symphytum, all of which merit special attention, but generally S. officinale, or common comfrey, and a hybrid species S.x uplandicum are most often used. The ladder of which is particularly suitable for the home garden because it is sterile and doesn’t spread by seed. The most available variety is called ‘Bocking 14’. These are upright comfreys which can grow 5′ tall. There are also rhizomatous species which only grow 6″-1′ high and spread to form a dense groundcover.
Comfrey is prized amongst herbalists for its incredible healing powers. Comfrey leaves and roots
contain a high concentration of allatoin– a substance that speeds cell renewal. It got the colloquial name ‘knitbone’ for its use in treating wounds and reducing inflammation from broken bones and sprains. It’s not a surprise that comfrey fulfills a similar ecological niche working to heal wounded and degraded soils. Comfrey is referred to as a mineral accumulator or dynamic accumulator for its ability to mine nutrients with its deep roots (which also loosen compacted soils). Those nutrients are then deposited in the aerial parts of the plant; being especially high in potassium, phosphorus, calcium, and nitrogen. When the aerial parts die back in the fall those nutrients assimilate into the surrounding soil. Gardeners can facilitate this process by intentionally cutting the plant down at strategic times for use as mulch around fruit trees, berry bushes, or in the veg garden. In the permaculture world we
refer to this process as ‘chop-n-drop’. Plant comfrey at the base of your fruit trees and simply chop-n-drop the material right in place; breaking the leaves and stalks into smaller pieces will accelerate decomposition but is not necessary. This is an effective way to build topsoil rapidly and reduce off-site inputs. From my experience I’ve been able to get anywhere from 3-5 cuttings throughout the season. One fella recently told me he cuts his back 7-8 times! I like to wait for the first flush of flowers in early summer because they provide excellent bee fodder.
Another strategy for utilizing comfrey’s amazing mineral accumulating capacity is to brew a fermented comfrey tea. This is a very easy procedure which entails chopping up a few handfuls of comfrey leaves and placing them in a 5 gallon bucket with water. Cover with a lid and let the mixture ferment outdoors for 1-2 weeks. Alternatively, start the batch by pouring boiling water over the plant material and letting it steep for a few hours then adding room temp. water to fill the rest of the bucket. The hot water method seems to extract more of the nutrients. You will know its ready when it has a strong stank…a good stank! Apply with a backpack sprayer diluted or undiluted. This fermented tea can be used a foliar feed or applied directly to the soil.
I grow comfrey around my compost bins and periodically add it to new piles or existing piles to jump-start the decomposition process. I also like to think that the comfrey roots capture any leached nutrients from the compost pile. One reason some people bash on comfrey is because its nearly impossible to get rid of as the tiniest piece of root will put on adventitious buds and sprout into a new plant. Easy to propagate? Ooooh yes! Aside from comfrey’s amazing medicinal qualities and numerous garden uses, it is also a very beautiful plant that can tolerate almost any soil type and will grow well in partial shade. Some ornamental varieties include ‘Goldsmith’, ‘Hidcote Blue’, and ‘Dwarf White’. I would love to hear how you’re utilizing comfrey in your garden! Cheers.
Short video clip: Comfrey Chop-N-Drop Timing