Spanish Lilac, Valerian: Sowing, Planting and Care

Description and Botany

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The Centranthus or Valerian is a herbaceous perennial plant that has recently been classified in the Caprifoliaceae family alongside honeysuckles, rather than in the Valerianaceae family like its close cousin, the common valerian (Valeriana officinalis).

It naturally grows in pebbles as well as in clay, in undergrowth, wet meadows, torrent banks, or along roads, on slopes and arid rockeries in mountainous regions worldwide, particularly in the Mediterranean regions from southern Europe to Asia Minor. It has naturalised in many areas of France.

The genus Centranthus comprises 8 species of perennials, annuals, or biennials. The few cultivated species are perennials valued for their flowering.

The most widespread species is Centranthus ruber, the Red valerian, also known as Garden valerian or Spanish lilac and its cultivars. The common valerian or “All-heal”, which belongs to a different genus, Valeriana, is also frequently found in our gardens where it has been cultivated for its medicinal properties since antiquity.

On a woody, fragrant stump anchored on short rhizomes, the Valerian rises in a beautiful rounded, bushy, and branched tuft, with a loose upright habit. The plant has a somewhat gangly appearance. It typically reaches 60 to 80 cm in height with a diameter of 50 cm, but can grow up to 1 m tall if the soil is suitable. Growth is rapid, and the plant has a good longevity in dry, poor soil.

The roots of Centranthus emit a characteristic scent, somewhat unpleasant but so attractive to felines that it has earned the nickname “Cat’s herb”.

The cylindrical, smooth, hollow, fleshy yet brittle stems, covered in bloom and branched at the tips, bear small deciduous to semi-persistent leaves depending on the mildness of the climate.

Several colours of Garden valerian: Centranthus ruber ‘Albus’, Centranthus ruber, Centranthus ruber ‘Coccineus’ (photo PAP)

The glabrous, fleshy leaves are opposite along the stems, simple, entire, or pinnatisect towards the base of the tuft, ovate, elliptical to lanceolate. They consist of 3 to 10 pairs of dentate leaflets. The basal leaves are short-petiolate, while the upper ones are sessile and sheathing.

Thick, they measure from 2 to 20 cm long and are jade green, bluish-green, or grey-green. The foliage of the Valerian is aromatic, and although it has a rather unpleasant smell, it can be incorporated into salads. While the roots of valerian are primarily used for their therapeutic virtues, the foliage also possesses medicinal, antispasmodic, and sedative properties.

Very floriferous, the Valerian offers a profusion of slightly fragrant flowers from spring to late summer.

From May until the first frosts in October, tiny star-shaped flowers, 2 to 5 mm long and flattened, appear above the foliage, grouped in branched corymbs or compact panicles at the tips of the fleshy stems.

The flowers of the Red valerian take the shape of a funnel. The corolla, composed of 5 petals, is distinguished from other valerian species by its long spur filled with nectar.

The flowering of valerian typically displays all shades of pink, ranging from crimson pink to rosy lavender, including red, and they are sometimes white or a lovely rosy white in the common valerian.

(©Philippe Giraud-Biosphoto)

They emit a subtle sweet and penetrating fragrance when they bloom and make excellent cut flowers for summer bouquets.

This abundant flowering and particularly nectar-rich attract the incessant flight of butterflies, bees, and bumblebees throughout the summer.

These delicate little flowers give way to small feathery achenes that the wind disperses here and there, sometimes even in quite curious places; it is not uncommon to find them between the stones of a wall and in the tiniest sunny corners!

Hardy beyond -20°C, resistant to summer drought and sea spray, the Valerian can be planted anywhere in France. Not demanding regarding soil type, it thrives in full sun, whether in stony or clayey soil, although it prefers light, calcareous, poor, and dry soils. Its cousin, the common valerian, prefers cool, moist soils and ideally partial shade.

The Centranthus is an almost foolproof plant, a boon for gravel gardens, dry rockeries, to flower the gaps in dry stone walls. It is an essential perennial in a wild garden with a rustic appearance or a vicar’s garden where it will add life to a large rockery, a large perennial bed, or to dry, inhospitable slopes that are well sunlit.

Centranthus ruber and Valeriana officinalis are both known for their sedative and relaxing properties.
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Main species and varieties

The Most Popular

Our Favourites

Centranthus ruber

This is the typical species. It thrives in both gravel and clay. It is ideal for colonising walls and dry areas of the garden.

• Flowering time June to September
• Height at maturity 70 cm

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Centranthus ruber Albus

A lovely wild valerian with white flowers. It has an exceptional flowering duration.

• Flowering time August, September
• Height at maturity 80 cm

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Valeriana officinalis

This plant has medicinal properties. Its flower stem can reach 1.5 m. Very hardy, it enjoys woodland, rockeries, and the edges of ponds. It naturalises well in wild gardens.

• Flowering time June to August
• Height at maturity 1,20 m

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Centranthus ruber Kempenhof

It bears lovely pink flowers. It can be grown everywhere, in borders, on dry banks or in rockeries, and in the cracks of old walls.

• Flowering time August to October
• Height at maturity 80 cm

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Centranthus ruber Coccineus

We love its rich colour! A vicar's garden flower, it self-seeds naturally and requires no care.

• Flowering time June to October
• Height at maturity 80 cm

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Centranthus ruber Star Ruber Mixed - Red Valerian Seeds

A mix of red, white, and pink valerian flowers. Easy to sow in poor soils of rockeries, banks, and on old walls.

• Flowering time June to November
• Height at maturity 1 m

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Snowcloud Garden Valerian Seeds - Centranthus ruber

A variety of garden valerian with white flowers! It is a very hardy perennial to grow in borders, on dry banks, or in rockeries.

• Flowering time June to November
• Height at maturity 1 m

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Planting

Where to Plant Valerian or Centranthus

Hardy down to -20°C, drought-resistant in summer and tolerant of sea spray, Valerian adapts to all types of climates. Undemanding in terms of soil type, it is a frugal plant that thrives in challenging conditions. It grows naturally in poor, dry, and sunny soils. Although it can tolerate any well-drained soil, it prefers dry, light, stony, even calcareous and low-fertility soils. Provide it with full sun or slightly shaded exposure: it sometimes tends to lean to seek out light.

While it can also grow in any soil, common valerian will thrive more in rich, cool, and moist but well-drained soil and in partial shade.

With its rustic and warm silhouette, Valerian adds charm to informal, cottage-style gardens, where it self-seeds spontaneously among trees and bushes.

With its rapid growth, garden Valerian is ideal for quickly flowering a poor bank, an unsightly old wall, or a brand-new garden; it is a born coloniser!

It stands out in Mediterranean gardens, in dry or gravel gardens, in borders, on slopes, in dry rockeries, and in perennial beds scorched by the sun, always bringing a sense of lightness to summer scenes.

Common valerian will find its place by ponds, in shaded woodlands, or in a bed or cool rockery.

Melliferous to the core, valerian flowers are useful in the vegetable garden.

When to Plant Valerian

Valerian can be planted either in spring, from February to May, or in autumn, from September to November, avoiding periods of drought and frost.

How to Plant Valerian

In the Ground

To plant garden Valerian or Centranthus ruber, do not add compost or fertiliser at planting; just a handful of pebbles or a scoop of gravel to improve drainage, as it has a clear preference for light soils.

Conversely, when planting common valerian, there is no need to add sand; instead, add compost, as it prefers rich, compact but well-drained soils that are slightly cool and moist.

For a quick and beautiful effect, plant at least 7 to 9 plants per m², spaced 30 to 60 cm apart in all directions.

• Soak the pots in a basin of water for 15 minutes before planting
• Dig a hole 2 to 3 times the volume of the root ball
• Loosen the soil well, carefully removing roots and stones
• Spread a good layer of gravel and sand at the bottom of the hole
• Place the root ball in the middle of the hole
• Fill the hole with the extracted soil, possibly mixed with river sand
• Lightly compact
• Water once a week to ensure establishment

Centranthus ruber ‘Kempenhof’

When and how to sow valerian seeds

How to sow valerian under cover

Valerian is sown from March to June. You can collect seeds from your garden from June until the frost or choose from our collection of false valerian or centranthus seeds. Seed germination takes 21 to 30 days.

• Sow your seeds generously in a seed tray filled with potting soil
• Lightly cover the seeds with potting soil
• Lightly press down and water thoroughly with a fine spray
• Place the seedlings in light, without direct sunlight, at a temperature of 18°C to 20°C
• Transplant the seedlings when they are about 5 cm tall into pots
• Install the young plants in the garden at the end of May to early June when temperatures are warm enough
• Space your plants about 30 cm apart

How to sow valerian in open ground

If the plants start to develop the following spring, you will need to be patient as they will not flower until three years later.

• In May, in well-warmed and well-worked soil, sow your valerian seeds generously
• Cover them with a thin layer of potting soil
• Press down
• Water thoroughly with a spray and keep the soil moist until germination
• Thin out by keeping one plant every 30 to 60 cm

Maintenance, pruning and care

How to Care for Garden Valerian or False Valerian

Once well established, Garden Valerian or Red Valerian knows how to be forgotten. It is so robust that it can do without watering, unless planted in the height of summer, and requires almost no maintenance. In well-drained soil, Valerians have no enemies and are insensitive to diseases.

Water once a week during the first summer following planting, but avoid overwatering.

No fertiliser is necessary as Garden Valerian is an undemanding plant.

The tallest Valerians may tend to flop and require staking.

Regularly remove faded flowers to encourage the renewal of flowering, and after the first bloom, cut back the withered stems by half to promote a resurgence at the end of the season.

It tends to self-seed easily in the most unexpected places if you haven’t cut all the flower spikes. Leave them to seed if you wish to benefit from spontaneous sowing.

How to Care for and Harvest Common Valerian

Common Valerian, unlike its sap sister, is more demanding: make organic fertiliser applications in spring and autumn.

Water it more regularly in summer as it prefers soil that remains cool.

Harvesting Valerian Roots

The roots of Common Valerian contain well-known active principles for their sedative and calming properties.

In autumn, using a fork, harvest its roots from well-established clumps. They are best consumed fresh, usually in herbal tea, but their flavour is very bitter.

Pruning Valerian

Cutting back is recommended after flowering as it encourages the growth of new, more elegant foliage.

At the end of winter, in February-March, using pruning shears, cut back the entire clump to 10-20 cm above the ground to promote branching.

Every 2 to 3 years, in spring or autumn, divide the clumps to rejuvenate the plants.

Multiplication

Les Valerianas self-seed abundantly and spontaneously, often in unexpected places if not cut back immediately after flowering. Seeds are harvested at ripeness, if you haven’t cut all the flower stems; otherwise, choose from our valerian seeds. Dividing clumps is also easy.

By sowing

Multiplying valerian by sowing is therefore a simple operation, but you can also collect and transplant spontaneous seedlings when the young plants have 5 or 6 leaves. Be aware that spontaneous seedlings rarely produce plants true to the parent, as the colours are random. To successfully sow valerian seeds, read our tips above.

Learn more in our tutorial: Valerian, Spanish Lilac: how to propagate it?

By division

Clumps of Valerian are divided in March from well-established mature clumps.

• Using a fork, gently lift the stump
• Separate a few clumps with roots
• Replant immediately in well-prepared soil
• Water regularly to encourage recovery

Associating valerian with the garden

With its slightly loose silhouette, the Valerian is a reliable choice for blurred gardens, cottage gardens, wild spaces, and vicar’s gardens. Easy to pair, Valerian evolves freely in a garden, quickly filling empty spaces between vicar’s garden perennials like hollyhocks and foxgloves, or summer-flowering shrubs such as lavateras or hibiscus.

An example of a cottage association: Centranthus ruber, Hardy geranium ‘Johnson’s Blue’, Rose ‘Iceberg’ and a pink rose like ‘Jacques Cartier’, Lychnis coronaria ‘Alba’ against a backdrop of Deutzia ‘Mont Rose’ (photo scene ©Andrew Lawson Flora Press – Biosphoto)

It is essential in a pink garden or white garden, where it adds a charming and romantic touch.

In a dry naturalist garden, it can be paired with spurges, centauries, poppies, and Damascus nigellas.

Its slightly diffuse habit will benefit from being combined with more sculptural plants like bearded irises, ornamental garlic, or sea holly.

For a profusion of flowers in an impressionistic composition, surround a few clumps of valerian with easy-going perennials that bloom generously, such as potentillas and hardy geraniums, which will spread in all directions and flower from May to August with little maintenance.

Another example of a more tonal association: white delphinium like ‘Galahad’, Oriental poppy like ‘Perry’s White’, Centranthus ruber ‘Albus’, and a daisy like Leucanthemum superbum ‘Becky’

With its true pink flowers, Valerian stands out in soft colour themes: opt for delicate combinations with silver-leaved plants like wormwoods, Echinops sphaerocephalus, helichrysum, dianthus, sedum, or lavenders.

In the height of summer, its soft hues will pair well with yarrow, monardas, agastaches, coreopsis, gauras, phlox, Spanish lawn, and cosmos. You can also mix valerian with its white-flowered cousins to create beautiful colour masses.

Red centranthus or red valerian will be perfect surrounded by herbaceous peonies and planted at the base of roses, adding an extra touch of grace and colour.

On a low wall, valerian will thrive alongside alyssum, campanulas, or aubrietas.