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Comfrey: Growing Comfrey - A Useful and Ornamental Herb

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Overview:

Comfrey was once a popular medicinal herb. We’ve recently learned that it can be a carcinogenic when taken internally, but it is still used as a topical treatment for skin irritations, cuts, sprains and swelling and as livestock feed and compost. Because of its tall stature and ease of care, comfrey is also a popular ornamental plant. Comfrey is in the same family as borage.

Latin Name:

Symphytum officinale

Common Name:

Common Comfrey

Hardiness Zone:

Light Exposure:

Full sun to Partial Shade.

Mature Size:

36 - 60" (h) x 24 - 48" (w)

Bloom Period:

Late spring through summer.

Description:

Comfrey shoots up quickly early in the season and can easily reach heights of around 5 feet. The lower leaves are equally large, somewhat dwarfing the hanging clusters of flowers at the top of the plant. The form and size of the plants might have you thinking it’s a shrub, but it will die back to the ground in the winter and it does not get woody.

Comfrey has a deep tap root, so it is extremely drought tolerant and a useful clay busting plant.

Leaves: Coarse and hairy with winged stalks and stems. Ovate to lance-shaped and dark green.

Flowers: Violet, pink or creamy yellow flowers born on forked cymes.

Suggested Varieties:

  • Symphytum officinale ‘Bocking’ - a sterile hybrid that doesn’t self-seed.

  • Symphytum officinale ‘Variegatum’ - has leaves with white margins

  • Symphytum Goldsmith’ - a shorter cousin with green, gold and cream variegation and pale blue flowers.

Design Suggestions:

Comfrey makes an interesting focal point in a border and is great for drawing the eye to the back of a border. I’ve seen it used nicely at the ends of vegetable beds and in the center of a 4-square herb garden.

The pale flowers and dark green leaves are set off nicely by chartreuse and bright clear yellows, like Cripps Golden’ Hinoki Falsecypress, Yellow Foxtail Grass (Alopecurus pratensis 'Aureus') or a Canary Vine running up through it.

Growing Tips:

Soil: Comfrey is widely adapted but it will thrive in a rich organic soil. As with all rapid growers, comfrey needs a lot of nitrogen. Comfrey gets all its nitrogen from the soil, so some type of regular organic matter is essential.

Comfrey is not particular about soil pH. A neutral to acidic range of 6.0 - 7.0 is ideal.

Planting Comfrey: Comfrey can be grown from seed, but it requires a winter chilling period to geminate. It’s not unusual to sow seed and not see any germination for 2 years.

If all you want is one comfrey plant, you can usually find them for a reasonable price in the herb section of local nurseries or by mail order. Plants can go outdoors once danger of frost has passed.

When starting several comfrey plants, it’s more common to use root cuttings. These are 2-6" lengths of root which are planted horizontally 2-8" deep. Plant shallow in clay soil and deeper in sandy soils.

You can also grow comfrey from crown cuttings, but these will be more expensive. A crown cutting will include several eyes and may grow faster than root cuttings, however the difference is negligible. Crown cuttings are planted 3-6" deep.

If you are growing several plants of comfrey for harvesting, space them in a grid, 3' apart.

Maintenance:

Once comfrey is established it will take care of itself. Each year the plant will get a little larger and the root system will get more dense. It is very hard to get rid of an established comfrey plant. Comfrey can live several decades before it begins to decline.

Because of its tap root, comfrey is very drought tolerant. However regular watering will keep it growing strong and blooming.

Harvesting: Comfrey

Leaves can be harvested and dried at any time. If you are growing it to harvest the leaves, you can make your first cutting when the plants are about 2' tall. Cut back to within a few inches of the crow. If you begin harvesting early, you won't get flowers.

Leaves, flowers and roots have all been used in traditional medicine, but use extreme caution if you don't know what you're doing. Comfrey should never be taken orally and even a topical application can cause problems.

One of the safest and easiest uses of comfrey is as a mulch for other crops. Comfrey leaves will slowly release all the nutrients their long tap roots pulled up from the soil. They're especially good around plants that like a little extra potassium, like fruits and tomatoes.

Pests & Problems:

No insects are known to be problems of comfrey. There is a comfrey rust that can overwinter in roots and decrease vigor and yield, but it is not common in most areas.

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