There are many benefits to growing comfrey. Learn how to grow this perennial herb and why it’s making its way into permaculture gardens everywhere.
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Many years ago, a friend gave me a comfrey plant. She swooned about the many benefits of growing comfrey. Without a doubt, I was excited, but a little skeptical about this so-called ‘super plant’. Could this one plant really have such a big impact?
After one season, that one plant appeared to make a difference in the health of my soil, so I rushed out to buy more plants!
This perennial herb grows in USDA hardiness zones 3-9. Although comfrey is tolerant of a variety of growing conditions, I’ve found it grows best in full to partial sun and in rich, loosened soil. The more compacted the soil is, the more shade it prefers.
Permaculture gardeners seek out plants that are multifunctional and help our gardens to work like mini-ecosystems, which saves us time. And you guessed it — comfrey is one of these plants!
The Benefits of Growing Comfrey
- Attracts pollinators with its blue, pink, purple, or white bell-shaped flowers.
- Provides habitat for beneficial insects under its huge leaves, which helps to keep the garden pest-free.
- Fertilizes with nutrient-rich mulch. Comfrey is known to be a nutrient accumulator, reaching its roots deep into the ground to mine the subsoil for nutrients (potassium, phosphorus, calcium, and more). Next, nutrients accumulate in the fast-growing leaves so you can use them as a fertilizing green mulch.
Here are one gardener’s soil test results before and after mulching with comfrey.
This herb even has amazing healing properties. Learn how to make your own comfrey salve!
Growing Comfrey for Different Uses
There are two types of comfrey that gardeners most commonly grow:
- True/Common comfrey (Symphytum officinale)
- Russian comfrey (Symphytum x uplandicum) also called the Bocking 14 cultivar.
Let’s take a minute to talk about the properties and uses for each.
This is the original ancient herb, nicknamed ‘knitbone’, that is grown for medicinal purposes.
The active medicinal substance in this herb, allantoin, is a cell proliferant, and has traditionally been used to heal broken bones, external injuries, and a host of other ailments. I use a comfrey poultice on bruises, and it helped me heal a scar on my face.
Comfrey is usually recommended for topical use such as in a healing salve. The leaves and roots are both used fresh or dried.
Recently, I noticed that allantoin is the primary healing ingredient in Whole Foods brand hand lotions.
In fact, the plant’s most potent concentration of healing properties occur just before flowering. As a result, this is the best time to cut it back for medicinal use.
Since this variety proliferates wildly from seed, cutting the plant before it flowers keeps it in check.
Because true comfrey is a prolific grower, you can cut the foliage back four to five times per year for mulch without any harm to the plant. However, true comfrey is most commonly grown for medicinal purposes.
Buy true comfrey as seed, live root, or plant. I like starting true comfrey from seed.
Would you like to learn more about using “super plants” like comfrey in your permaculture garden?
You’ll find loads of information just like this in my award-winning book, The Suburban Micro-Farm.
Russian Comfreys (Bocking 14 or Bocking 4)
These cultivars are named after Bocking, England where they were developed.
They’re a hybrid of true comfrey and another variety called prickly comfrey. While true comfrey can spread easily, Russian comfrey has sterile seed, so it won’t take over the garden.
That benefit, plus the fact that it is a vigorous grower, is why many permaculture gardeners grow it as biomass for mulch.
This is what really makes this plant a star in the permaculture garden: its ability to feed the soil with nutrient-rich leaves. Mulch with the leaves to transfer those nutrients to the soil.
Vegetarian gardeners looking for non-animal fertilizers will find this herb to be a valuable source of nutrients and green manure.
Although the Bocking varieties do not proliferate by seed, the plant will grow in width and eventually need to be divided. And that’s how you can produce more of these plants for mulch over time!
Buy this cultivar either as live root cuttings or as a plant. Because the seeds are sterile, you can’t grow it from seed. I like to plant Russian comfrey root cuttings.
Comfrey will be there a long time, so choose your site well for planting. It can be planted almost any time of year that the soil is workable.
Simply avoid the dead of winter when the ground may be frozen, as well as super wet periods when soil shouldn’t be disturbed. In addition, avoid the height of summer when temperatures in your area are at their peak.
When planting root cuttings or mature plants, soak them in water beforehand for about an hour. I recommend this for all of your perennials because it helps them transition to their new home more easily.
Whether planting root cuttings, mature plants, or seeds, plant them about three feet apart.
Planting Root Cuttings
My preference for is planting root cuttings of Russian comfrey, which are more economical than purchasing mature plants. Additionally, digging a small hole for planting root cuttings is easier than the larger hole needed for mature plants.
Dig a small hole 2 inches deep in clay soil or 4 inches deep in sandy soil. Lay the root cutting down laterally and cover. Top with a high-nitrogen mulch, such as manure or clippings of grass or clover, and water well.
Planting Mature Plants
Use a digging fork to loosen the soil where you intend to locate the plants and dig a hole at least 1 foot deep. Loosen soil at least 6 inches below the plant. So the bigger the plant is, the deeper you should dig and loosen.
Mix in manure or rich compost at the time of planting. Water well and top with mulch.
Sowing comfrey seeds is only possible for true comfrey, so only go this route if you have a lot of space and don’t mind the plants spreading over time.
Sow seeds in the spring when the ground is workable to a 1/2-inch depth and three feet apart.
Growing Comfrey for Mulch
This is an excellent herb to grow for chop-and-drop mulch around perennial edibles. See how I use it under fruit trees in my article How to Build a Fruit Tree Guild.
Chop the leaves into pieces and use them around the garden for a fertility boost. Chopping the large leaves into pieces allows them to break down faster and prevents the mulch from forming a mat on the soil surface.
Read more about this practice in my article Mulching in the Permaculture Garden.
In the picture below, I’m preparing to spread buckets of true comfrey mulch around the garden. However, I’ve separated the flowers so as not to spread seeds around the garden.
I have to be diligent about chopping down my true comfrey plants before the flowers drop their seeds, but otherwise, true comfrey is easy to work with.
After five years, I’ve never had more than a couple of volunteer plants develop around the garden. If you notice the volunteers while young, they’re easy to dig up and transplant, or throw in the compost for a nutrient boost.
Both varieties can be used for medicinal purposes and mulching purposes interchangeably, by the way. It’s just important to remember whether or not you have the sterile seed variety, so you know how to manage the plants in the garden.
- Does Comfrey Really Improve Soil?
- 7 Ways to Fertilize the Garden with Comfrey
- The Lazy Gardener’s Way to Make Fertilizer
Do you grow comfrey in your garden? Which type do you grow?