Comfrey is one of our favorite companion plants, and much of that appreciation comes from its famously deep root system.
Comfrey’s thick, resilient roots play an important role in improving compacted soil. This effect is especially noticeable in areas with strong seasonal changes. During wet periods or nutrient rich spring conditions, the roots swell as they absorb water and minerals. During dry conditions, portions of the roots naturally die back and slough off, leaving behind channels in the soil.
These channels improve water infiltration, aeration, and root access for surrounding plants. Over time, this creates healthier, more resilient soil with less intervention.
What About the ‘Dynamic Accumulator’ Moniker?
Yup, you may have heard comfrey described as a dynamic accumulator. Essentially, because its roots extend several feet into the ground, comfrey can access minerals from deep soil layers that many other plants cannot reach. These nutrients are stored in the leaves, which is why comfrey leaf compost and mulch are known for being especially nutrient-rich. While more research is being done, one SARE-funded trial found that comfrey is particularly a dynamic accumulator of potassium and silicon.
Back to Companion Planting…
So, we know comfrey does a lot. The question then, is where should you grow it???
Berry Patches
Between berry bushes is one of our favorite places to plant comfrey. We often place a comfrey plant between each currant, gooseberry, raspberry, blackberry, or blueberry in a row. The size of the plant can be managed through regular chop and drop harvesting. Starting with a smaller plant is helpful so it does not overwhelm young berry bushes, as comfrey can be very difficult to stop once fully established.
Fruit Trees
Comfrey also works beautifully near fruit trees. We plant it about four to five feet out from the trunk and cut the leaves regularly, dropping them toward the tree’s drip line. We mulch our fruit trees at least five feet from the base and place comfrey just beyond that zone.
Vegetable Gardens
Now, we typically avoid planting comfrey directly in garden beds due to its aggressive growth and perennial nature. Instead, we plant it close by so it is easy to harvest leaves for mulching potassium-loving crops like tomatoes, potatoes, and peppers.
Landscaping Beds
Comfrey also fits well into landscaping beds. Because it attracts pollinators and produces abundant biomass, we like to plant it near larger ornamental or perennial plants that benefit from regular chop and drop mulching.
Slopes & Drip Lines
Technically, this isn’t companion planting, but we think it’s worth a mention.
On slopes, comfrey has proven to be an excellent stabilizing plant. Its perennial root system helps hold soil in place, slows runoff, and supports long term establishment in areas prone to erosion. For the same reason, comfrey can also be planted along building drip lines to help reduce erosion caused by repeated runoff from roofs.
A Warning About Placement
Comfrey is very difficult to move once established. Even small root fragments left in the soil can regrow into new plants. For this reason, thoughtful placement is essential. We have found that repeated mowing can weaken comfrey over time and may eventually eliminate it, but removal is slow and requires persistence.
Choosing the Right Comfrey Variety
Common comfrey, Symphytum officinale, spreads readily by seed. While that may not be a problem if you’re growing comfrey at scale, it becomes difficult to control the spread when using comfrey as a companion plant or in garden settings.
For this reason, we strongly recommend the sterile comfrey cultivar Russian Bocking 14. It spreads only through root divisions, making it far easier to manage while still providing exceptional biomass and soil-building benefits.
Comfrey is easy to grow from root cuttings and is a wonderful companion plant, especially for orchards and berry patches. We think everyone should be growing it (although I admit we’re slightly biased here). Hopefully this has given you a better idea of how you can best utilize comfrey on your property, and you can reap the benefits of companion planting.
Disclaimer: Comfrey is not recommended to take internally, because it contains pyrrolizidine alkaloids (PAs), which are linked to liver toxicity and possibly cancer. We are not medical professionals, and are not offering medical advice. Please consult your doctor or a medical professional if you have any medical concerns.