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Comfrey Plant: How to Grow This Productive, Pollinator‑Friendly Perennial

Purple flowers of comfrey (Symphytum officinale) in bloom.

Comfrey (Symphytum officinale) produces clusters of purple, bell-shaped flowers that attract bees and other pollinators.

Photo Credit
Kristof Lauwers
Botanical Name
Symphytum officinale
Plant Type
Perennial Flowers
Sun Exposure
Full Sun
Part Sun
Soil pH
Slightly Acidic to Neutral
Bloom Time
Spring
Summer
Fall
Flower Color
Purple
Pink
White
Hardiness Zone
4
5
6
7
8
Special Features
Attracts Pollinators
Attracts Bees
Attracts Butterflies

Why Comfrey Is Such a Helpful Plant in the Garden

Written By: Lauren Landers Master Gardener and Contributing Writer

Comfrey may not look like a miracle plant, but it may just heal your garden!  Not only does this unassuming perennial appeal to pollinators, but its leaves make a fantastic organic fertilizer and compost additive. Further, it was traditionally used as a medicinal plant. If you’re looking for an overachieving perennial that’s attractive and useful, here’s why comfrey is an excellent choice and growing tips to keep it comfy in your garden.

About Comfrey Plants

There are around 40 to 60 species of comfrey, which are mostly native to Europe and Asia. These plants all belong to the borage family and are closely related to borage, oyster plants, and forget-me-nots. However, common comfrey (Symphytum officinale) is the most well-known type and grows up to 3 feet tall. It is easily recognized by its large, slightly hairy leaves and clusters of bell-shaped flowers that are highly appealing to bees, butterflies, and other beneficial insects.

Comfrey plant with purple, bell-shaped flowers growing in a garden.
Comfrey (Symphytum officinale) growing in the garden with clusters of purple flowers. Kristof Lauwers

For centuries, comfrey was widely grown as a medicinal plant to treat wounds, broken bones, and a range of other ailments. But today, comfrey is mostly cultivated as an ornamental, and it’s a fine choice for cottage gardens, pollinator habitats, medicinal herb beds, and more. I personally love growing comfrey with plants like coneflowers, phlox, and black-eyed Susan that also appreciate full sun and moist soil. Just keep in mind that comfrey is an aggressive and potentially invasive plant and is not recommended for every garden.

Aside from its beauty, comfrey also has several practical uses and can improve garden soil over time. Packed with nutrients like potassium, magnesium, phosphorus, and nitrogen, comfrey leaves can be dug directly into garden beds to feed plants like tomatoes. They can also be chopped and added to compost piles as a compost accelerator. You can even steep comfrey leaves in water for about six weeks to create an all-natural liquid fertilizer for indoor and outdoor plants!

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Planting

Fast-growing comfrey can be grown either from potted plants or seed. However, because these plants are native to cold regions, they germinate best when their seeds are cold stratified before planting!

When to Plant Comfrey

Potted comfrey should be planted after the last frost of spring, while comfrey seeds can be directly sown outdoors in fall. If you miss your fall planting window, you can also cold stratify comfrey seeds in the fridge for 4 weeks, sow the seeds in pots in mid-spring, and set the started plants outside after the risk of frost has passed.

How to Plant Comfrey

  • To sow potted comfrey, gently remove the plant from its pot and tease apart encircling roots. Dig a hole that’s slightly larger than your plant’s root ball, amend the excavated soil with compost or aged manure, plant the comfrey at the same depth it was growing in its old container, add mulch, and water well.
  • To sow comfrey seeds in fall, prep your planting site before the ground freezes by removing weeds and raking compost into the soil. Sow comfrey seeds ¼-inch deep in pairs, space multiple seed pairs 2 to 3 feet apart, mark the location to keep track of your plants, begin to water the seeds in spring, and thin out the extra comfrey plants when the seedlings are 2 to 3 inches tall.
  • To sow comfrey seeds in spring, sow pairs ¼-inch deep in seedling pots filled with seed-starting mix. Keep the seeds in bright light, water regularly, thin out the extra seedlings when they’re 2 to 3 inches tall, and transplant the seedlings outdoors once the risk of frost has passed.

Growing

Hand reaching toward small purple comfrey flowers on a growing plant.
A gardener’s hand reaches toward the flowers of comfrey (Symphytum officinale) in bloom. Credit: Lipatova Maryna

Comfrey can grow aggressively, so I like to plant it in raised beds to control the spread of its roots. Combining this with deadheading the flowers before they drop seed should manage comfrey’s spread; however, it’s best to avoid growing comfrey near plants that it can easily overwhelm or crowd out. Eradicating unwanted comfrey is difficult as these plants can regrow from a small section of root left in the soil.

Once established, comfrey has a long bloom time with flowers lasting from May to September. I find this plant looks particularly appealing when grown in groups near the rear of my flower beds, or in wide spaces where these vigorous growers can spread out. Comfrey’s large roots make it hard to keep in containers, but these plants can be maintained in 5-gallon pots if needed.

Water
Established comfrey plants are drought-tolerant, but these plants still grow best in moist, well-draining soil. Young comfrey should be watered regularly, but I only water my established plants during long periods of drought or when the top 2-inches of soil feels dry.
Light
Full sun to part shade locations are suitable for growing comfrey, as long as the plants receive at least 3 hours of direct light. In hot climates, locate comfrey in a spot that receives light afternoon shade to limit heat stress.
Humidity
Comfrey can handle both low and high humidity conditions as long as its roots have enough moisture.
Temperature
Hot and cold weather doesn’t bother comfrey much. These plants are hardy in zones 4 and up, but grow better in light shade in hot areas.
Fertilizer
Fertilizer is not needed with comfrey. Just apply an annual application of compost in spring or fall.
Toxicity
Comfrey plants are toxic to pets, livestock, and humans and should not be consumed.

Types

Caucasian comfrey plant with bright blue flowers in bloom.
Not all comfrey is purple—Caucasian comfrey (Symphytum caucasicum) blooms bright blue. Credit Wirestock.

If you find a plant labeled as simply “Comfrey” at a plant nursery, there’s a good chance it’s common comfrey. But as you can see, there are lots of other fantastic comfrey varieties to try.

  • Common Comfrey (Symphytum officinale): The most popular type of comfrey, common comfrey grows up to 3 feet tall and produces pinkish-purple flowers from spring to early fall.
  • Wild Comfrey (Cynoglossum virginianum): A rare comfrey that’s native to central North America, this plant produces pale blue flowers.
  • Caucasian Comfrey (Symphytum caucasicum): Also known as blue comfrey, this stunner produces color-changing flowers that shift from pink to blue as they age.
  • ‘Bocking 14’: This sterile comfrey cultivar doesn’t self-seed and is a good choice if you’re concerned about comfrey’s invasive tendencies. These plants can still spread by their roots, though!

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Pests/Diseases

Easy-to-grow comfrey plants are immune to most pests and diseases and naturally resistant to deer and drought. Despite all this, even hardy comfrey can still succumb to a few issues in the garden.

  • Slugs and snails may feed on comfrey leaves and flowers, but they can be controlled with slug pub traps.
  • Comfrey rust looks like fine yellow speckles on the underside of comfrey leaves, which can cause poor plant growth. Unfortunately, this disease is difficult to manage, and infected plants should be destroyed.

Propagation

Comfrey is a prolific self-sower and will naturally spread by its roots and seeds when left to its own devices. You can also divide comfrey using the following steps to create more plants for your garden.

  • Dig up a section of comfrey plants in March to Apriljust as the plant’s shoots are emerging from their winter snooze.
  • Use a knife or a garden spade to cut the plant’s crown into divisions, each with healthy stems and roots.
  • Plant the divisions 3 inches deep as soon as you can and water regularly until your new comfrey plants start growing!

Seasonal Care
To keep comfrey happy, add compost and mulch over your plant's roots once a year in spring or fall. No other winterization is needed.

You can prompt these plants to flower more prolifically by trimming the plant’s stem to 6 inches above the soil line during the plant’s first year. Pruning after this point is optional and only necessary to control the size and spread of comfrey plants.

If you don’t want comfrey to grow aggressively, deadhead the flowers when they fade. Comfrey leaves can be harvested with pruners or scissors several times throughout the growing season if you want to use comfrey for compost or fertilizer. That said, you may want to wear gloves when harvesting comfrey as the leaves can be a skin irritant for sensitive individuals.

Wit and Wisdom

  • Comfrey flowers lure in both long-tongued and short-tongued bees. Long-tongued bees feed directly from comfrey flowers in the usual way, but short-tongued bees may act as “nectar robbers” and nibble holes in comfrey flowers to access the tasty nectar inside.
  • Traditionally used to treat a range of ailments, comfrey is also sometimes known as “knitbone,” “slippery root,” and “black wort.” The name Symphytum comes from the Greek ‘symphyo’ meaning ‘knit’ and ‘phyton’ meaning ‘plant’, and refers to comfrey’s healing abilities.
  • Comfrey leaves can also be harvested to create a bright green dye!

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About The Author
Lauren Landers

Lauren Landers

Master Gardener and Contributing Writer

Lauren is a gardener, writer, and public speaker with over a decade of experience helping others learn about gardening, homesteading, and sustainable living.She combines years of practical gardening a...
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