Symphytum asperum
Weedy and Potentially Invasive: Do Not Plant
Common Name: prickly comfrey 
Type: Herbaceous perennial
Family: Boraginaceae
Native Range: Europe, Caucasus, Iran
Zone: 4 to 8
Height: 2.00 to 4.00 feet
Spread: 2.00 to 4.00 feet
Bloom Time: May to July
Bloom Description: Rose-pink changing to blue or purple
Sun: Full sun to part shade
Water: Medium
Maintenance: Medium
Suggested Use: Naturalize
Flower: Showy
Tolerate: Deer, Drought
This plant has been found to be weedy and potentially invasive and should not be planted in Midwestern gardens.

Culture

Easily grown in average, medium moisture, well-drained soils in full sun to part shade. Best in moist, organically rich soils in part shade, but has respectable drought tolerance and can do reasonably well in dry, shady locations. Tolerates close to full shade. Plants may spread somewhat aggressively by creeping rhizomes and by self-seeding, and can be quite invasive in the garden. Moreover, once planted, comfrey can be very difficult to dig out because any small section of root left behind can sprout a new plant. Easily propagated by seed, root cuttings or division. Trim foliage as needed to shape plant. Cutting back stems promptly after flowering may encourage additional bloom.

Noteworthy Characteristics

Symphytum asperum, commonly called prickly comfrey or Persian comfrey, is a coarse, hairy, rhizomatous perennial that is typically grown in shaded wildflower areas or naturalized areas for its attractive foliage and spring flowers. It grows to 3-4' tall. Ovate to elliptic leaves (to 2-8" long) are dark green and prickly hairy. Mature stems are not winged (leaf bases are not decurrent as is the case with Symphytum officinale. Small tubular flowers (each to 1/2" long) in scorpioid cymes open rose-pink in spring but mature to blue or purple. Flowers bloom May to August. This plant is native from Russia (Caucasus) to Iran. It has naturalized in parts of southern Canada, the northern U.S. and along the U.S. Pacific coast. Plants are cultivated for silage (fodder) in Russia.

Genus name comes from the Greek words symphyo meaning to grow together and phyton for plant as the plant was believed to help heal wounds.

Specific epithet means rough in reference to plant texture.

Common name or comfrey comes from the Latin words "con" and "firma" meaning "with strength" in reference to its reputation for healing wounds and broken bones.

Problems

No serious insect or disease problems. This species is classified by the California Department of Food and Agriculture as a noxious weed - List B.

Garden Uses

Naturalize in woodland gardens, shade gardens, cottage gardens, herb gardens, wildflower meadows or naturalized areas where plants can form colonies over time. Perhaps too coarse for borders.