Red valerian

Red valerian: how do you recognise it?

Habit

Bushy, upright perennial 60–80 cm tall and 45–60 cm wide; the base becomes woody after a few years.

Leaves

Oval to lance-shaped, 5–10 cm long, opposite, blue-green and slightly fleshy.

Flowers

Small tubular flowers with a narrow spur, in dense, domed clusters at the stem tips, from May to October.

Colour

Pinkish red; there are also white and deep red forms. Seedlings may differ in colour from the parent.

Seed

Each seed has a fluffy parachute and blows away like a dandelion’s: it self-seeds readily.

Roots

A thick, fleshy taproot: move it while young, as older plants re-establish poorly.

Flowering: May–October · Sowing: March–May · Plants: March–May and September–October · Pruning: March and July–August

Why grow it?

• Flowers for almost half a year, from May to October, especially if you cut back faded stems.
• A true butterfly plant: butterflies, hummingbird hawk-moths, bees and bumblebees visit it all summer.
• Grows where other plants give up: in dry, poor soil, between stones and even in wall joints.
• Needs no watering after its first year, not even in dry summers.
• Looks lovely in a gravel garden, a rock garden, on a bank or on top of a low wall.

Red valerian: where does it grow best?

• Full sun; in shade it flowers less and flops open.
• Poor, free-draining soil: sand or light loam, neutral to chalky. Also between stones and in old walls.
• Dry is fine; it dislikes wet, heavy soil in winter.
• On rich soil it grows soft and falls over: no compost or fertiliser in the planting hole.
• Allow 40–50 cm between plants.

Light

Sun

Soil type

Sand or loam

Acidity

Neutral or chalky

Moisture

Dry

Size

0.7 m tall, 0.6 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Lavender: The same dry, sunny spot; purple beside pinkish red.
• Mexican fleabane: A small white-and-pink daisy that also loves growing in walls.
• Catmint: Long blue flowering and a great bee plant too.
• Mediterranean spurge: Blue-green leaves and lime-yellow spring flowers in the same dry soil.
• Mexican feather grass: An airy grass that sways between the flower clusters.

Red valerian: when and how to plant it?

Plant in March–May and September–October.

1. Plant from March to May or in September–October, preferably young pot-grown plants.
2. Dig a hole slightly wider than the root ball and, in heavier soil, mix in some coarse sand or gravel for good drainage.
3. Set the plant at the same depth as it was in the pot and firm the soil well.
4. Space plants 40–50 cm apart.
5. Water well when planting, then during dry spells for the first few weeks.
6. If you like, spread gravel around the base instead of compost: it keeps the crown dry.

Care

Water

Only in the first year, during long dry spells. Once established it manages without.

Feeding

Not needed. Fertiliser makes the plant floppy and less free-flowering.

Deadheading

Cut faded stems back to just above a few pairs of leaves: it will flower again and self-seed less.

Seedlings

Weed out seedlings in the wrong place while small, before the taproot goes deep.

Renewal

After 4–5 years it becomes woody and bare at the base. Replace it then with a seedling or a cutting.

Tip: After the first flush in July, cut the stems back by half: it flowers again in August and you limit self-seeding. Do leave a few clusters if you want seedlings to replace old plants.

Red valerian: when to prune it?

Pruning months: March and July–August.

When: After the first flush of flowers in July, faded clusters in August, and a tidy-up of old stems in March.

How:

• In July, cut faded stems back by about half: a second flush follows a few weeks later.
• In August, remove faded clusters before they turn fluffy if you want to limit self-seeding.
• In March, cut old, dead stems back to just above the new leaves at the base.
• Let a few clusters set seed if you want young plants to replace old, woody ones.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Indoors in March–April or outdoors in April–May, barely covering the seed. Seedlings usually flower from the year after sowing.

Basal cuttings

In spring, take cuttings of young shoots from the base and root them in a sandy cutting compost.

Self-sown seedlings

It self-seeds freely. Move seedlings while they are still small, keeping the taproot intact.

Red valerian: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: in Belgium it comes through a normal winter without protection.
• Wet soil is more dangerous than frost: make sure drainage is good.
• In a pot or container: stand it against a wall, out of the worst rain, and make sure there is a drainage hole.
• Leave the old stems until March; they give the crown a little protection.

Diseases and pests

• Root rot: The plant collapses and discolours, usually in wet, heavy soil in winter. Replant in a drier spot or on a raised mound with gravel.
• Floppy growth: Soil too rich, fertiliser or too much shade. Don’t feed, choose a sunny spot and cut back after the first flush.
• Aphids: On young shoots in spring. Ladybirds usually deal with them; otherwise hose them off.
• Too many seedlings: Remove faded clusters before they turn fluffy and weed out seedlings while young.
• Bare centre: Older plants turn woody. Replace them after a few years with a seedling or cutting.

Through the year

• March: Cut back old stems. Plant. Sow indoors.
• April: Plant. Sow outdoors. Take basal cuttings.
• May: Flowering begins. Still time to plant.
• June: Full flower. Butterflies and bees visiting.
• July: After the first flush, cut stems back by half.
• August: Second flush. Remove faded clusters to limit self-seeding.
• September: Flowering. Plant or move seedlings.
• October: Last flowers. Plant.
• November: Dormant. Leave old stems until March.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• The name Centranthus comes from the Greek words for ‘spur’ and ‘flower’: each tiny flower has a narrow spur at the back holding nectar.
• Each flower has just one stamen, which is fairly unusual among flowering plants.
• The seed carries a parachute of fine hairs, so the wind takes it to walls and rock crevices, where the plant often turns up of its own accord.