The Purple-Flowered Landscape Powerhouse
Scientific Name: Symphytum sp.
Other Common Names: Russian comfrey, common comfrey, boneset, knitbone
USDA Hardiness: 2
Useful Properties: medicinal, livestock forage,dynamic accumulator, pollinator attractor
Let's start with the kinds of comfrey:
- Common/true comfrey (Symphytum officinale) is a non-hybrid variety that can produce (and spread) via fertile seed. For some people, its ability to spread indescriminately is a problem. It typically grows up to 3 feet tall.
- Russian comfrey (Symphytum x uplandicum) is a natural hybrid and is futher classified into cultivars, with Bocking 4 and Bocking 14 being the most commonly available. (Don't let the whole 'Bocking' thing confuse you. It just refers to the town in England where a lot of the research and hybridization was initially done. There are actually 21 cultivars, Bocking 1-21.) Russian comfrey does not reproduce from seed, but will easily reproduce via root cuttings. This is great for those of us who want more of it, but can be problematic if you want to clear it our of a space. It can grow a little larger than common comfrey; 4 feet is not uncommon.
We'll focus mostly on Russian comfrey here, but many of the same attributes hold true for common comfrey. Generally, the differences between Bocking 4 and 14 are relatively small and they can both fulfill the same niche in your landscape. Bocking 4 may send it's roots a little deeper, but both will do a good job helping to break up soil. Bocking 14 is more commonly used as fertilizer because the thinner stems decompose more quickly, whereas Bocking 4 is commonly used for livestock feed. In general, I'm not sure it will make a whole lot of difference for most people. If you were looking to have fields of one or the other, it might be worth differentiating. However, for most of us who just want this amazing plant around, just use what you can get and either will do well for you.
Getting to the heart of the matter: comfrey is an awesome plant that belongs in your planning. It has a stack of uses/functions:
- Great dynamic accumulator of nutrients. Chop-and-drop to recycle those nutrients for other nearby plants. Another common practice is to make a comfey tea for application to other plants.
- It's highly productive and can usually be cut 3-5 times per year for mulch/fertilizer or animal feed.
- High protein animal feed -- 20-30% protein in dried comfrey. That places it far above other common protein sources for livestock, like legumes.
- Pollinators enjoy the umbel-shaped blue/purple flowers. I'm not a good pollinator, and I like them too. (You'll see other colors as well, including pinks. Blue/purple seems the most common.)
- Comfrey has a long history as a medicinal. Did we mention it's called 'boneset' and 'knit bone'? Poultices including comfrey have traditionally been used to help heal cracked bones as well as sprains. It's also excellent for any skin condition. In fact, it's so good that you don't want to use it on deep cuts because it can cause the skin to heal too quickly over the open wound, leading to possible infection!
There are different camps on using comfrey internally. It does contain compounds that can cause liver damage and other issues and in the US the FDA has banned the marketing of comfrey products intended for internal use. However, many people note that the amount of comfrey you would have to consume to have a toxic effect is very large; in the long history of comfrey's medicinal use, there are few (any?) cases where it can be firmly cited as causing any issue. So the moral here is: do your homework and make your own educated decision.
Note: All material is educational and not intended to be medical advice or indicate treatment for any specific disease or condition.