How to Grow and Care for Comfrey

Comfrey (Symphytum officinale) is a perennial wildflower that grows along riverbanks and in grasslands in its native habitat. The flowers in the late spring and summer attract bees and other pollinators, which makes comfrey a welcome addition to a wildflower garden.

The plant grows slightly taller than it is wide. It has large, pointed, dark green, aromatic leaves up to 8 inches long with a coarse, hairy texture. The lower leaves tend to be larger than the upper ones. Comfrey has a vigorous growth rate and can be planted at any time when the soil is not frozen.

Comfrey is toxic to humans and pets.

Comfrey Care

Comfrey is highly adaptive to a variety of growing conditions and requires very little maintenance. Here are the main care requirements for growing comfrey:

• Plant it in a location with full sun or partial shade with good drainage.
• Water young plants until they are established and mature plants during prolonged dry spells.
• Amend the soil with plenty of compost.
• Promptly remove the spent blooms to prevent the plant from spreading its seeds.
• To protect the roots against winter cold, cover the base with a thick layer of mulch in the fall.

Light

Comfrey grows in full sun to partial shade. It needs at least three hours of direct sunlight on most days. In the warmer parts of its hardiness range, plant it where it get shade from the strong afternoon sun.

Soil

The plant tolerates a wide range of soil conditions, including clay soil and somewhat sandy soil. But it prefers organically rich, loamy soil with good drainage.A slightly acidic to neutral soil pH is ideal, but the plant tolerates slightly alkaline soil as well.

Water

Comfrey plants prosper with an even amount of soil moisture. They have some drought tolerance once they're established but prefer at least a moderate level of water. Be sure to keep the soil of young plants consistently moist but not soggy. Water mature plants whenever the top inch or two of soil begins to dry out.

Temperature and Humidity

Comfrey is hardy both to the extremely cold and hot temperatures within its growing zones. Humidity typically isn’t an issue for comfrey as long as adequate soil moisture is maintained.

Fertilizer

There is no need for any commercial fertilizer; the best feeding regimen for comfrey is to provide regular organic amendments to the soil, such as a layer of compost applied each spring.

Tip

Comfrey leaves make an excellent liquid fertilizer. If you don't want to wait six weeks for the leaves to break down, you can also use them as mulch or leaf mold, in compost, or as a soil additive.

Types of Comfrey

In addition to common comfrey, there are about 60 other species in the Symphytum genus. Other types of comfrey that are of interest to gardeners include:

• S. caucasicum (Caucasian comfrey). also called blue comfrey, is valued for its flowers that start pink but then transition to a bright blue.
• S. grandiflorum: (large-flowered comfrey) features showy cream-colored to white blooms.
• S. x uplandicum (Russian comfrey) is a sterile hybrid that does not produce seeds. It grows up to 6 feet tall and sports violet flowers. A popular cultivar, ‘Axminster Gold’, has large, banana-shaped variegated leaves with broad yellow leaf margins. 'Bocking 14' is another cultivar that does not produce viable seeds.
• Cynoglossum virginianum (wild comfrey) is a rare comfrey native to North America sometimes called houndstongue or giant forget-me-not. It is in the same plant family as the other comfrey species but belongs to a different genus. It has a single flowering stalk about 2 feet tall with a pale sky-blue flowers.

Pruning

After the plant has finished blooming for the first time, cut it back to 6 inches above the ground to stimulate new growth. In the following years, prune individual stems as needed to control the size and shape of the plant.

Propagating Comfrey

Propagating comfrey from crown cuttings in the spring is the easiest and most reliable way to propagate the plant.

1. In March or April, just as the plant is breaking dormancy and new shoots are emerging. cut horizontally through the crown about 3 inches deep using a sharp spade or a knife. Trim off a healthy-looking segment of the crown that has roots and shoots.
2. Plant the segment horizontally in a new location, about 3 inches deep. Plant them less deep in clay soil, deeper in sandy soil.
3. Keep the soil consistently moist (but not soggy) until you see growth.

How to Grow Comfrey From Seed

Comfrey seeds require 30 days of cold temperatures to germinate, that's why they are best directly sown outdoors in the fall. Plant the seeds 1/4 inch deep, spaced 24 to 36 inches apart. and mark the location well. Keep the soil consistently moist during the germination period, which takes 14 to 21 days.

Potting and Repotting Comfrey

Because of its deep and extensive root system, comfrey is not a good choice for potting. Unless you plant it in a large container of at least 5 gallons capacity, it will do poorly in a confined space. However, you can start growing comfrey from cuttings for the first season in a container, and once it is established, plant in the garden.

Overwintering

When the plants die back in the winter, cover them with a heavy layer of mulch or manure. This protects the roots from the cold.

Common Pests and Plant Diseases

Comfrey is generally not bothered by any serious pests or diseases. The only exception is comfrey rust, a fungal disease where the undersides of the leaves are covered with lots of tiny orange-yellow spots. The fungus weakens the plant's growth and flowering. It is hard to get rid of and it is best to dig up and dispose of infected plants in the trash because the spores typically overwinter in the roots. Slugs and snails also might damage the foliage, but deer tend to leave the plants alone.

How to Get Comfrey to Bloom

Bloom Months

Comfrey typically blooms from May to September. In ideal conditions, it starts producing flowers in late spring and continues into the late summer.

What Do Comfrey Flowers Look and Smell Like?

The tiny flowers are bell-shaped and grow in drooping clusters. Depending on the variety, their color ranges from white or cream to purplish, sometimes striped, The flowers aren't fragrant but the leaves are.

How to Encourage More Blooms

Cutting back the stems after the first flowering may result in a second bloom.

Common Problems With Comfrey

Comfrey tends to be invasive. Mature plants grow an extensive root system, including a deep taproot, which allows them to efficiently obtain nutrients and moisture from the soil and up into the leaves. This also makes comfrey plants difficult to eradicate. Any small portion of the root left in the soil after you dig up a plant likely will grow a new plant. To contain it, grow it in a pot or raised garden bed instead of in the ground. Also, make sure to remove the spent blooms so the plant won't reseed itself, or select a sterile cultivar such as 'Bocking 14' to prevent reseeding.

From: thespruce