Comfrey: A plant worthy of love that’s essential for every garden

  • The best way to get new comfrey plants is to divide mature ones into smaller “starter” plants. (regenfarms.com via Diana Duff/Special to West Hawaii Today)

  • Comfrey roots often grow nearly 10 inches into the soil. (horizonherbs.com via Diana Duff/Special to West Hawaii Today)

  • Comfrey is often used on hillsides for erosion control. (goodlifepermaculture.com.au via Diana Duff/Special to West Hawaii Today)

  • The flowers of the true comfrey usually appear as small deep purple bells. (wikimedia.org via Diana Duff/Special to West Hawaii Today)

  • The Russian Comfrey Block #4 is probably the most desirable variety with low alkaloids and high soil nutrient content. (garden.org via Diana Duff/Special to West Hawaii Today)

  • The hairy stems of the comfrey plant often catch dew and glisten in the morning sunlight. (aphotoflora.com via Diana Duff/Special to West Hawaii Today)

My introduction to comfrey, more than 30 years ago, remains a wonderful memory.

I was a newbie farmer and full of enthusiasm. I arrived as a volunteer at Harvey Sacarob’s organic farm in Honaunau around 6:30 a.m. Standing in the dim early morning light with a few other bleary-eyed volunteers, we watched sunlight creep up the terraces on the hill at the back of the farm. A row of comfrey plants fronted each terrace of vegetables. As the golden light gradually buttered the ridge, it touched each row of comfrey in its path. The plants sparkled and twinkled as the sunlight hit the dew caught in their fuzzy leaves. I wept at the sight and fell in love with comfrey that day.

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Comfrey is definitely a plant worthy of love. Its numerous features make it an essential plant for every garden. At Harvey’s farm, the vegetable terraces were well protected against erosion by the presence of comfrey. He also used the comfrey leaves to add nutritional value to his compost or to place on the soil as mulch and a nutrient enhancement.

Comfrey is a member of the Boraginaceae (Borage) family and is related to the herb borage as well as the indigenous native Hawaiian kou and an endemic variety of hinahina. Like borage, comfrey leaves are covered in tiny hairs giving them a fuzzy look and feel. Beyond the botanical classification, however, comfrey has very few similarities to its other family members.

True comfrey (Symphytum officinalis) has a long history in temperate as well as tropical locations as a useful plant and medicinal herb. It was traditionally known as “knitbone” or “boneset” and was used as a healing tea or poultice for injuries including broken bones. Recently, scientists have found some comfrey varieties contain pyrrolizidine alkaloids, which may be toxic to the liver. The Food and Drug Administration now advises that comfrey only be used externally.

Evidently, some varieties contain very little of this alkaloid and offer a highly nutritional soil amendment. The variety named Russian Comfrey Blocking #4 (Symphytum x uplandicum) is probably the best choice for low toxicity and high nutrients. Its leaves are particularly high in N-P-K and can be harvested often to be used as mulch, cut up to use as green manure or added to enrich compost. The seeds of this variety are sterile however, so the plant can only be propagated vegetatively.

In its native habitat in temperate zones of Europe and Asia comfrey grows in damp, grassy locations, often on the banks of rivers. True comfrey does produce seeds and can spread easily becoming somewhat invasive. The Russian hybrid’s sterile seeds make it easier to control.

All comfrey varieties can be propagated by division. Regular division can reduce the size and crowding of your comfrey plants. Every few yours you may want to divide the plant(s) and their roots into several starter plants. Slice through the plant with a sharp knife or shovel creating small starter plants. Cut back most of the leaves and plant the starters in a place that gets at least a half day of sun. Young plants will do best in soil that drains sell and gets regular watering. Once established, comfrey is somewhat tolerant of dry spells.

True comfrey can be grown from seed, but requires a chilling period to germinate. This can be achieved by refrigerating the seeds for several months in the winter. The seeds may also be very slow to germinate, sometimes taking more than a year to sprout. If you can find gardeners willing to divide their plants, root division may be the way to go. Otherwise, look for young plants in a nursery.

Comfrey is often grown as an attractive garden addition as well as for its many other benefits. The plant constantly produces upright green leaves that form an attractive clump several feet wide and between two and three feet high. The deep green leaves can be harvested throughout the year for nutritious biomass for the garden as well as to use for healing purposes

Seasonally comfrey plants will put up thin, hairy stalks that hold clusters of small bell-shaped flowers in various shades of blue or purple. These pretty flowers attract bees and other pollinators to the garden. Only true comfrey produces viable seeds following flowering, however.

Comfrey’s deep root system can grow up to ten inches into the soil. This is what makes comfrey such a good choice for holding soil on a slope to prevent erosion. The roots are also valuable medicinally.

With so many positive features and uses, you can see why I love the plant and recommend that it be planted in every garden.

Diana Duff is a plant adviser, educator and consultant living part time in Kailua-Kona.

Gardening Events

Every Saturday: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Come with a mask and be prepared to practice social distancing. Volunteers can help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Call Peter at 323-3318 for more information.

Thursday: “Webinar on Priaxor Xemium Use for Coffee Leaf Rust” 4-5:30 p.m. Register at www.HawaiiCoffeeEd.com/priaxor or by calling Matt at (808) 322-0164.

April 17: “Macadamia Orchard Management Workshop” 10 am to noon at Hawai’i Macadamia Nut Services in Pahala. Free. Limit to 20 participants. Contact Tanner at tannerkeys@gmail.com for any questions. Register at https://www.eventbrite.com/e/integrated-orchard-management-tickets-145774518509.

Available online: “Brochure on Hawaii Leaf Rust” available at HawaiiCoffeeEd.com/CLRtrifold or by contacting Andrea Kawabata by e-mail at andreak@hawaii.edu, by text at (415) 694-1511 or phone at (808) 322-4892.

“Video on Little Fire Ants” with new information from the Hawaii Ant Lab and Hawaii Tropical Fruit Growers at https://www.htfg.org/post/learn-about-little-fire-ants

Save the Date: “Coffee Berry Borer & Coffee Leaf Rust Conference 2021” on April 16 and 17 from 9 a.m. to 12:30 p.m. on Zoom

Registration is at https://cbb-clr2021.eventbrite.com

Farmer Direct Markets (check websites for the latest hours and online markets)

Wednesday: “Ho’oulu Farmers Market” at Sheraton Kona Resort & Spa at Keauhou Bay

Saturday: “Keauhou Farmers Market” 8 a.m. to noon at Keauhou Shopping Center

Information on their online market at keauhoufarmersmThursarket.com/onlinemarket

“Kamuela Farmer’s Market” 7:30 a.m. to noon at Pukalani Stables

“Waimea Town Market” 7:30 a.m. to noon at the Parker School in central Waimea

“Waimea Homestead Farmers Market” from 7:30 a.m. to noon at the Waimea middle and elementary school playground

Sunday: “Pure Kona Green Market” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook

“Hamakua Harvest” 9 a.m. to 2 p.m. at Highway 19 and Mamane Street in Honoka’a

Plant Advice Lines

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Anytime: konamg@ctahr.hawaii.edu; Tuesdays and Thursdays from 9 a.m. to noon at UH-CES in Kainaliu at (808) 322-4893.

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