Red valerian

Sun

Full sun is best; tolerates light shade but flowers less heavily and may become floppy.

Water

Water regularly while establishing; once rooted, water only during prolonged drought. Avoid persistently wet soil.

Soil

Well-drained, lean to moderately fertile soil, including chalk, limestone and gravel. Tolerates alkaline conditions; struggles in wet clay.

Height

2-3 ft (0.6-0.9 m)

Spread

1-2 ft (0.3-0.6 m)

Flowers

Late spring through summer, often repeating into early autumn after cutting back; usually rosy red to pink, with white-flowered forms also available.

Foliage

Fleshy, smooth, blue-green to grey-green leaves in opposite pairs; lower leaves have stalks and upper leaves clasp the stems.

Growth

Fast

Care needed

Low

• Pollinators
• Drought tolerant
• Heat tolerant
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.7 ft (0.53 m)

3. After 2 years

   2.5 ft (0.75 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Invasive in

the US and Australia

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Plant in freely draining soil, keeping the crown out of wet hollows.
• Water new plants until established, then let the soil dry between waterings.
• Avoid rich manure and routine feeding, which encourage weak, floppy growth.
• Use a light gravel mulch rather than moisture-retentive material around the crown.
• Pull unwanted seedlings while small; established plants develop stubborn roots.

Pruning. Cut spent flowering stems back to leafy growth after the main flush to encourage another crop of flowers and prevent seeding. Remove dead stems in early spring, leaving any healthy basal foliage.

Early spring

Remove winter-damaged stems and check that the crown is not sitting in wet soil.

Spring

Plant into well-drained ground and water new plants during dry spells.

Late spring

Pull unwanted seedlings before their roots become established.

Summer

Cut back spent flower stems to leafy growth for repeat flowering.

Early autumn

Remove remaining flower heads before seed disperses, especially near natural areas.

Winter

Keep the crown free of wet leaves and avoid watering established plants in damp weather.

• Plant in gravel gardens with lavender and catmint for loose colour above low, drought-tolerant planting.
• Use in sunny cottage borders, where its branching flower stems soften more upright plants.
• Grow on dry banks or beside sound stone retaining walls, removing seedlings from mortar joints.
• Repeat small groups along sunny paths to bring flowers and butterflies close to view.

Garden styles it suits: Cottage garden, Mediterranean, Dry gravel garden, Pollinator garden, Coastal and Low-maintenance.

Plant it with: Lavender, Catmint, Yarrow, Lamb's ears, Bearded iris and Rock rose.

Wildlife: Nectar-rich flowers attract butterflies, bees and other pollinating insects over a long season.

• Crown and root rot in wet soil: improve drainage or move the plant to a raised, gravelly position; replace badly rotted plants.
• Excessive self-seeding: cut off fading flower heads before seeds form and pull seedlings promptly.
• Floppy stems in shade or rich soil: move to full sun, stop feeding and cut back after flowering.
• Aphids on soft shoots: wash them off with water and allow ladybirds and other predators to control small colonies.

Not known to be toxic to people, cats, dogs or horses. No poisonous part is established, though animal-specific safety information is limited; do not treat it as a food plant or substitute it for medicinal valerian.

Where it spreads. Listed as invasive in California and regarded as an environmental weed in parts of southern Australia, including Western Australia, South Australia and Victoria. It self-seeds readily into rocky ground, walls and disturbed sites; check local guidance before planting and avoid it near vulnerable natural habitats.

• Common valerian (Valeriana officinalis)

  Common valerian has divided leaves with many leaflets and pale pink or white flowers; red valerian has simple, undivided leaves and usually deeper pink-red flowers.

• Sweet William (Dianthus barbatus)

  Sweet William has flatter flower heads with conspicuous five-petalled, often toothed flowers; red valerian has many tiny tubular flowers with a slender spur.

Centranthus comes from Greek words for spur and flower, referring to the spurred blooms, while ruber is Latin for red.

Propagation. Sow seed in spring, or take basal cuttings in spring to preserve a particular flower colour. Self-sown seedlings are easy to transplant when young but may differ from the parent; do not propagate where the plant is locally invasive.

Accepted botanical name

Centranthus ruber

In the US and Canada

Introduced in Hawaii and the lower 48 states.

Sources: GBIF (CC BY 4.0) and USDA PLANTS. The care and design notes are LandscapeGPT's own.