Prickly comfrey (Symphytum asperum)
Discover Prickly comfrey (Symphytum asperum), a coarse, hairy perennial perfect for naturalizing, blooming rose-pink to blue.
Complete Plant Information
Overview
Prickly comfrey, scientifically known as Symphytum asperum, is a robust, coarse, and hairy rhizomatous perennial well-valued for attracting attention in naturalized settings. Ideal for gardeners seeking hardy coverage, this plant establishes quickly, producing attractive dark green foliage throughout the growing season. Its aesthetic appeal is enhanced by charming tubular flowers that transition in color from rose-pink to deeper blue or purple shades as they mature.
This species is native across Europe, the Caucasus, and Iran, bringing a touch of Old World resilience to the garden landscape. Though it prefers moderate moisture, Symphytum asperum’s respectable drought tolerance allows it to persist even in drier, partially shaded conditions once established. Be aware that Prickly comfrey can spread via rhizomes and aggressive self-seeding, making it an excellent choice for large natural areas but potentially invasive in manicured beds.
Functionally, this plant has historical uses, though modern gardeners integrate it primarily for its dense coverage and early summer bloom display. Understanding the spreading nature of Prickly comfrey is key to successful integration, reserving its use for areas where its vigor can be fully appreciated without encroaching on less hardy neighbors.
Fast Facts
- Plant Family: Boraginaceae
- Plant Type: Herbaceous perennial
- Native Range: Europe, Caucasus, Iran
- Hardiness Zones: USDA Zones 4-8
- Size at Maturity:
- Height: 2-4 ft
- Spread: 2-4 ft
- Bloom Time: May to July
- Bloom Description: Rose-pink changing to blue or purple
- Sun Exposure: Full sun to part shade
- Water Needs: Medium
- Maintenance Level: Medium
How to Grow
Symphytum asperum thrives when planted in average, medium-moisture, well-drained soils. While it tolerates various conditions, the best performance, including the richest foliage color, is achieved in organically rich soils situated in partial shade. Planting during spring or fall allows the plant time to establish its powerful root system before summer heat or winter cold arrives.
Care requirements for Prickly comfrey are relatively straightforward, classifying it as medium maintenance. Water moderately, ensuring the soil does not completely dry out, particularly during its first year of establishment. While it possesses drought tolerance, consistent moisture enhances vigor. No specific fertilization is usually needed if planted in moderately rich soil; excessive fertility may encourage even more aggressive spreading.
Routine maintenance focuses largely on managing its spread and appearance. Trim back stems as needed to maintain shape or encourage secondary bloom after the primary flush fades in mid-summer. Because Symphytum asperum spreads vigorously by creeping rhizomes, diligence in removal or containment may be necessary if placed where its colonization is unwelcome. Division or root cuttings are easy methods for propagation if you wish to move or multiply the plant.
Landscape Uses
The primary recommended use for Prickly comfrey is to naturalize large areas, allowing this vigorous grower to form dense, self-sustaining colonies. It integrates beautifully into woodland gardens where its coarse texture contrasts nicely with finer ferns and hostas. It is also effective when introduced into cottage gardens or wildflower meadows seeking robust fillers that bloom reliably through early summer.
Due to its height (up to 4 feet) and potentially coarse appearance, Prickly comfrey is generally discouraged near formal borders or in small container arrangements unless rigorously contained. Instead, position it where its naturalizing tendency can be utilized, such as on slopes or open, less formal areas where its foliage and flowers can cover ground effectively. When used in masses, the changing purple and pink blooms create a dynamic visual texture.
Standout Features
Flower Qualities
- Showy
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, featuring ovate to elliptic leaves that are dark green and prickly hairy. Small tubular flowers open rose-pink in spring but mature to blue or purple, blooming consistently from May into August across the growing season.
Tolerances
- Deer
- Drought
Potential Problems
Generally, Prickly comfrey does not suffer from serious insect pest or disease issues, contributing to its easy-care reputation. However, its most significant “problem” is its aggressive growth habit. Symphytum asperum is classified by certain agricultural bodies, such as the California Department of Food and Agriculture, as a noxious weed—specifically List B—due to its ability to rapidly colonize areas via creeping rhizomes and plentiful self-seeding. Preventing spread is crucial; take care when digging, as even a small root fragment left behind can regenerate an entire new plant.
To manage this vigorous nature, plant Prickly comfrey only where competition from other less vigorous perennials is not a concern. If removal becomes necessary, complete soil excavation of roots is required, a challenging task given the plant’s strong hold. Containment via buried edging or regular division in the first few years can help monitor its expansion.
Frequently Asked Questions
What hardiness zones is Prickly comfrey suitable for?
This herbaceous perennial performs best in USDA Hardiness Zones 4 through 8, offering reliable overwintering in these regions.
How large does Symphytum asperum grow?
At maturity, Prickly comfrey generally reaches a height between 2 and 4 feet and spreads outwards to a similar width of 2 to 4 feet.
When does Symphytum asperum bloom?
You can expect the characteristic blooms of Symphytum asperum, which change from rose-pink to blue or purple, to appear throughout the peak summer period from May to July.
What sun exposure does Prickly comfrey need?
This plant adapts well to a range from full sun, where it requires consistent moisture, down to partial shade, where it exhibits respectable drought tolerance.
Conclusion
Symphytum asperum, or Prickly comfrey, offers a durable, low-maintenance option for gardeners looking to fill large, naturalized spaces with textural foliage and unique, changing summer flowers. Its strength lies in its resilience and impressive coverage, provided its spreading tendencies are accounted for during the initial planting design. Before you establish this Persian comfrey variety, confirm that your growing zone falls within USDA 4-8 and dedicate space appropriate for its vigorous nature.
Propagation Tips
The reliable nature of Symphytum asperum means propagation is quite easy, though care must be taken regarding invasiveness. The plant can be readily increased by seed, which often leads to the color variation seen in mature plants. For more controlled multiplication and to ensure the exact characteristics of the parent plant remain, utilize root cuttings or division of established clumps.
Division is best performed in early spring or fall when the plant is active but temperatures are mild. Carefully dig up the clump and separate the rhizomatous root mass ensuring each new section has several viable growth nodes. This technique is usually more effective for managing the large, spreading nature of established Prickly comfrey than relying solely on seed dispersal.
Companion Planting
Because Prickly comfrey enjoys rich soil but can handle some shade, it pairs well with other woodland or meadow edge plants that appreciate similar conditions. Consider planting it near shade-loving ferns which benefit from the soil enrichment provided by its foliage breakdown. In areas with full sun, it can inhabit the back of a border alongside robust bloomers like ornamental alliums or Russian sage, as long as its aggressive root spread is managed through physical barriers.
