Comfrey Plant Guide: How to Grow and Care for Comfrey

Comfrey (Symphytum officinale) is a perennial herb of the borage family that’s native to Europe and Asia. Comfrey, which stems from the Latin word “symphyo” meaning “grow together,” has been cultivated for more than two thousand years for culinary and topical medical uses. For its ability to promote cell growth, thanks to the cell proliferant allantoin, comfrey was known as “knitbone” and “boneset” in some cultures. Ancient Greek medicine used comfrey topically in the form of poultices, ointments, and salves. Today, gardeners and horticulturists grow comfrey for its beneficial effects on gardens and local ecosystems.

Comfrey can be dangerous for internal use. Comfrey contains pyrrolizidine alkaloids, which, if present in the body at high enough levels, can cause serious liver damage. Keep comfrey plants away from pets and children.

There are several wild species of comfrey, and a few cultivars and varieties. If you are interested in adding comfrey to your garden, consider the following kinds:

1. 1. True comfrey: True comfrey (S. officinale), also known as common comfrey or Quaker comfrey, is native to Europe and has a long history of medicinal and garden use. True comfrey features cream or purple flowers.
2. 2. Rough comfrey: Rough comfrey (S. asperimum), also known as prickly comfrey, gets its name from its especially hairy leaves. This comfrey plant produces red, pink, purple, or blue flowers.
3. 3. Russian comfrey: Russian comfrey (Symphytum x uplandicum) is hybrid of S. officinale and S. asperimum. Russian comfrey is sterile and does not propagate by seed, so it is easy to control in the garden. This hybrid comfrey, which features blue or violet flowers, is the most common kind of comfrey in the United States.
4. 4. 'Axminster gold': 'Axminster gold' is a striking cultivar of Russian comfrey that has green and yellow leaves.

Comfrey is a resilient, tenacious plant that’s simple to grow. Follow these steps to add the plant to your garden:

1. 1. Consider the climate. Comfrey is suitable for USDA hardiness zones through nine. The plant isn’t particularly picky about the pH of the soil it's planted in; usually, 6.0 to 7.0 is ideal. Plant them in well-draining, moist soil. Comfrey plants will become more drought-tolerant as they mature, but young plants need a good amount of moisture.
2. 2. Choose a permanent location. Comfrey will keep growing back from even a small amount of root left behind. It’s best to plant it where you want it to stay for a long time, and be on the lookout for spreading.
3. 3. Plant comfrey in a sunny spot. Pick an area with full sun to partial shade. During the first year, the plant will be sending down its large taproot and gaining its footing in your garden; it’s best not to disturb it too much.
4. 4. Give comfrey plants space. In order to grow and thrive to its full potential, a comfrey plant needs space. Three-foot spacing between the individual plants is ideal.
5. 5. Water the plants moderately. If you live in a particularly dry climate, make sure the plants do not wilt. It’s good to water them whenever the top two inches of soil are noticeably dry. Comfrey plants grow best with a moderate amount of moisture, and if you see them beginning to wilt, give them some water—they will likely bounce back.

Comfrey is a fast-growing, relatively low-maintenance plant. To make the most of this plant in your garden, consider the following care tips and uses:

1. 1. Let your comfrey plant bloom. Allow your comfrey plant flower at least once a season, as this will attract beneficial pollinators and provide your garden with a beautiful splash of color from the bell-shaped flowers.
2. 2. Prune the leaves. After the first year, you can cut the comfrey leaves back several times over a growing season so the plant does not overgrow. Comfrey will flower multiple times in a season. If you have more than one area where comfrey is growing, stagger your cutting, so you will have flowers blooming at different times.
3. 3. Make much from clippings. You can use the plant’s abundant biomass to make green mulch. Use the cut leaves to help add nutrients and moisture to other parts of your garden that require it. When you repeatedly cut the leaves back, this will cause some root die-back, which is also beneficial, since the decomposing organic root matter will add to the soil’s levels of potassium, phosphorus, and nitrogen. The sturdy, deep roots also help break up more dense, clay soils.
4. 4. Use the leaves to make fertilizer. Comfrey tea is another way to prepare the leaves as an organic fertilizer in liquid form. Spread the solution in the areas where the soil needs supplements.

Comfrey is simple to propagate by seed if you have a variety that produces seeds, or for the more common varieties, by cuttings or root division. Comfrey root cuttings are hardy and a great way to propagate. Split a mature plant down the middle, root and all, cut the roots into smaller sections, approximately six inches, and replant them horizontally.

Grow your own garden with Ron Finley, the self-described "Gangster Gardener." Get the MasterClass Annual Membership and learn how to cultivate fresh herbs and vegetables, keep your house plants alive, and use compost to make your community—and the world—a better place.