Red valerian (Centranthus ruber var. coccineus)

Overview

Centranthus ruber var. Coccineus, commonly known as Red valerian, is a valued, bushy, woody-based perennial appreciated for its long bloom period even in challenging garden spots. This cultivar specifically offers deep crimson red flowers, distinguishing it with the deep coloration referenced by its specific epithet, coccineus. It is extremely resilient, flourishing in poor, well-drained soils where many other ornamentals struggle.

Native to the Mediterranean region, this species has successfully naturalized in cooler summer climates along the West Coast of the U.S. Both Red valerian and Centranthus ruber var. coccineus provide dense terminal clusters of spurred, star-shaped flowers that contribute significant color from late spring until frost if maintained. Beyond aesthetics, prompt deadheading is crucial for preventing the prolific release of dandelion-like seed heads.

Gardeners utilize this plant for its hardiness and its ability to establish quickly on slopes or walls, offering good cover. While valued for its visual appeal and fragrance, gardeners must be mindful of its vigorous spreading nature in ideal conditions.

Fast Facts

• Plant Family: Caprifoliaceae
• Plant Type: Herbaceous perennial
• Native Range: Mediterranean
• Hardiness Zones: USDA Zones 5-8
• Size at Maturity:
  • Height: 1.5-3 ft
  • Spread: 1.5-2 ft
• Bloom Time: May to June
• Bloom Description: Crimson red
• Sun Exposure: Full sun to part shade
• Water Needs: Medium
• Maintenance Level: Medium

How to Grow

The best results for Centranthus ruber var. coccineus are achieved when planted in full sun, though it tolerates light afternoon shade. This perennial adapts well to average to sandy, medium-moisture soils, provided drainage is excellent. It exhibits a preference for slightly alkaline conditions; consider amending acidic soil by incorporating limestone to encourage robust growth.

Watering requirements are generally medium, but once established, the plant displays good drought tolerance, often thriving in drier spots where it develops a more compact habit. Fertilization is generally unnecessary, particularly since rich soils can lead to overly floppy growth. The key component of care involves managing its spread if you do not want it to naturalize heavily.

To maximize bloom production, promptly remove (shear if necessary) spent flower stems immediately after they fade. This essential task prevents the formation of wind-dispersed seeds, thereby controlling self-seeding. Be aware that in the hot, humid summers of the Southeast, the vigor of Centranthus ruber var. Coccineus can sometimes diminish compared to performance in cooler summer regions.

Landscape Uses

Red valerian is highly effective where rugged good looks are required alongside functional stability. It is an excellent choice for cottage gardens due to its slightly informal, abundant flowering habit. Furthermore, it excels in naturalized areas where its hardiness allows it to populate space rapidly.

The plant’s tolerance for poor media makes it ideal for difficult sites like stone walls, where its roots can find purchase in crevices. For slopes or banks, planting in masses of Centranthus ruber var. coccineus helps combat erosion effectively. When used in borders, plant it in smaller groups or as specimens where its spreading tendencies can be managed more easily than in large sweeps.

Standout Features

Flower Qualities

• Showy
• Fragrant
• Good Cut

Noteworthy Characteristics

Centranthus ruber, commonly called red valerian or Jupiter’s beard, is a well-branched, bushy, clump-forming, woody-based perennial which is valued for its ability to produce, often in poor soils, a showy bloom of star-shaped pink to red flowers from spring to frost. Flowers appear in dense terminal clusters (cymes) atop upright stems rising above the foliage to 1.5-3’ tall. Centranthus ruber var. Coccineus primarily varies from species plants by being somewhat more compact in size and by having dark crimson red flowers.

Tolerances

• Drought
• Erosion

Potential Problems

Centranthus ruber var. Coccineus generally avoids serious insect or disease issues under proper conditions. Occasional minor infestations by mealy bugs or aphids may occur but rarely cause lasting damage. The primary threat is crown rot, which will develop rapidly if the plant is situated in overly moist or poorly drained soils. Gardeners should also be aware that the invasive spread via abundant self-seeding can be troublesome, requiring consistent shearing of spent flowers to maintain control.

Frequently Asked Questions

What hardiness zones is Red valerian suitable for?

Red valerian is hardy across USDA Zones 5 through 8, making it a reliable perennial in many temperate climates.

How large does Red valerian grow?

This perennial typically reaches a manageable height between 1.5 and 3 feet tall, with a spread ranging from 1.5 to 2 feet wide.

When does Red valerian bloom?

You can expect the showy blooms of Centranthus ruber var. coccineus to appear primarily from May through June, with potential rebloom if deadheaded.

What sun exposure does Red valerian need?

This plant performs best when positioned in an area receiving full sun, although it will tolerate conditions with partial shade.

Conclusion

The resilient nature and vibrant crimson blooms make Centranthus ruber var. coccineus a valuable, low-demand addition to robust garden designs. Its tolerance for poor soils and dry conditions ensures success where other plants fail, particularly when used for stabilizing banks or walls. Assess your local USDA Hardiness Zone compatibility and plan to plant in the spring or fall for the best establishment of your Red valerian.

Companion Planting

When designing beds around Centranthus ruber var. coccineus, select companions that share its preference for well-drained and slightly alkaline soil conditions. Companion plants that bloom later in the season can take over aesthetically once the initial flush of Red valerian fades. Consider pairing it with sturdy Mediterranean natives like Lavender (Lavandula) or Greek Oregano (Origanum vulgare), which appreciate similar sun exposure and dry soil. These combinations create a drought-tolerant, fragrant border that showcases varied textures throughout the summer.

Wildlife Benefits

The unique, spurred structure of the Centranthus ruber var. Coccineus flower is highly attractive to specific beneficial insects. The flower clusters offer a rich nectar source, drawing in numerous types of butterflies throughout the blooming period. While the seed heads are often removed due to invasiveness concerns, leaving a few spent stems standing might provide late-season foraging opportunities for smaller beneficial insects before deep frosts settle in.