Dense clusters of small red flowers, likened by the botanist De Candolle to a red spearhead, crowd the stems of red valerian (Centranthus ruber) from late spring to early autumn. Give it full sun and it will flower in poor, dry soil where little else settles, needing no care at all.
| Name | Centranthus ruber |
|---|---|
| Family | Caprifoliaceae (honeysuckle family), into which the Valerianaceae family was merged |
| Type | perennial |
| Height | 24 to 40 inches (60 to 100 cm) |
| Exposure | full sun |
| Soil | ordinary, or even poor |
| Flowering | late spring to early autumn |
Its shrub-like stature and beautiful blooming make it a very ornamental plant.
Sowing red valerian
Sowing red valerian from seed is performed under cover at the end of winter and directly in the ground in spring, after any risk of freezing has disappeared.
Red valerian needs sun to develop and bear flowers.
If you sow at the end of winter, in a sheltered place:
If you sow directly in the ground:
Planting red valerian
It is recommended to plant your red valerian in spring or in fall spacing them 12 inches (30 cm) apart.
If you’re planting red valerian in spring, remember to water a bit more at the beginning.
Red valerian is a plant that propagates naturally through its seeds, but it is also possible to perform crown division.
Red valerian can be raised from seed under cover, sown straight where it is to grow, or increased from an established clump. The table sets out when each is done and how far apart the plants end up.
| Method | When | Spacing | Key point |
|---|---|---|---|
| Sowing under cover | End of winter, in a sheltered place | Transplant every 12 to 16 inches (30 to 40 cm) after late spring | Sow in a tray and keep the soil mix a little moist |
| Sowing directly in the ground | Spring, once any risk of freezing has disappeared | Thin to every 12 to 16 inches (30 to 40 cm) | Break up the soil first, then water with a fine drizzle |
| Planting young plants | Spring or fall | 12 inches (30 cm) apart | Water a bit more at the start if planted in spring |
| Crown division | Fall | As for planting | Divides an existing clump rather than relying on seed |
Left to itself, red valerian will also seed around without any help.
Centranthus ruber is nearly always sold as a colour form rather than a heavily bred cultivar, so the choice comes down to flower colour and how you mean to use it. The table below sets out the named forms most often found in seed catalogues and garden centres.
| Variety | Flower colour | Height band | Best use |
|---|---|---|---|
| ‘Coccineus’ | Deep carmine red | Medium | Bold colour in a sunny border |
| ‘Atrococcineus’ | Dark crimson | Medium | Strongest red for contrast planting |
| ‘Albus’ | Pure white | Medium | Cooling white scheme, evening interest |
| ‘Roseus’ | Soft pink | Medium | Pastel borders and cottage planting |
| var. coccineus | Bright red | Medium | Reliable red for poor, dry soil |
Red valerian is definitely an extremely easy plant that requires no care at all.
You can cut off wilted flowers when they die off if you wish, but this is only aimed at making it look nicer and won’t influence plant behavior.
Remove the flower heads before the feathery, dandelion-like seeds ripen if you would rather not have red valerian seedlings appearing in every wall crevice and gravel path.
There is no plant that is easier to care for than red valerian, and on top of this, it doesn’t even fear diseases or parasites.
In damp, still spots, crowded plants are more prone to powdery mildew on lower leaves; spacing needs vary by species, and thinning to improve airflow reduces the risk without guaranteeing control.
Red valerian, or Centranthus ruber, owes its name to the botanist De Candolle, who likened its flowers to a red spearhead (kentron means spear in Greek, and anthos means flower and ruber means red).
Native to the Mediterranean area, red valerian has the incredible capacity to grow in all types of soil, even the driest ones.
Lastly, red valerian is often said to share into the sedative properties of its cousin medicinal valerian.
Important to know: Red valerian is related to the Valeriana family. Inside all these plants is valproic acid, a compound that helps relax. It has been shown that eating any during pregnancy, especially at the beginning, resulted in more birth defects (1 to 2% added risk) in the children. These include spina bifida, atrial septal defect (a hole in the heart), hypospadias (in boys, an abnormality in the urethra), polydactyly (extra fingers/toes), craniosynostosis and cleft palate. Do not use this herb while pregnant or if hoping to be!
