Spur valerian (Centranthus ruber) is easy to grow, low maintenance, and bushy stems produce an abundance of star-shaped flowers that have an impressively long bloom time. It's a hardy perennial that adds a wonderful splash of vivid color to any garden.
Though it spreads aggressively and rapidly, it is still not considered invasive. Plant seeds after the threat of frost has passed for quick blooms to start in late spring and early summer and lasting through fall.
|Botanical Name||Centranthus ruber|
|Common Name||Spur valerian, red valerian, Jupiter's beard|
|Plant Type||Herbaceous perennial|
|Mature Size||Up to 3 ft.|
|Sun Exposure||Full sun/partial shade|
|Soil Type||Tolerant of a variety of well-drained soil types|
|Soil pH||Preference for alkaline|
|Bloom Time||Summer to early fall|
|Flower Color||Commonly crimson red, but also pale pink and white|
|Hardiness Zones||5-8 (USDA)|
|Native Area||Mediterranean region|
Spur Valerian Care
This old-fashioned wildflower is a great choice for cottage gardens as it'll grow in the cracks of chalky walls and pavers. The cut flowers also look great in a bouquet. The young, fresh, but bitter leaves and the plant's roots also have culinary uses in soups and salads.
Providing your spur valerian gets plenty of sun, you won't have to worry about any complicated or high-maintenance growing requirements. This hardy plant is tolerant of poor, infertile soils, and dry conditions. It's also easy to grow from seeds, root divisions, and cuttings.
Virtually free from pests and disease, spur valerian has a strong fragrance and pollinators can't resist this flower that blooms throughout the summer. Some gardeners find the fragrance unpleasant while others find it sweet. Its deep roots make the plant work well on slopes to help prevent soil erosion.
Spur valerian does best in a full sun position. It can tolerate partial shade too, but it may not produce quite as impressive a bloom through the summer. The plant may flop over if it's too shaded.
If you're looking for a plant that will thrive despite poor soil conditions, spur valerian would be a good choice. It copes with dry, infertile soils incredibly well and will flourish in a compact form in areas where many other plants die off.
It does prefer a slightly alkaline soil type. Limestone can be added to create better growth conditions if your soil is more on the acidic side. If the soil you're planting in is a richer variety, you may find that the tall spur valerian will benefit from staking.
A drought-tolerant plant, spur valerian doesn't need a lot of water. Young seedlings will need light watering, but established plants can cope fine with natural rainfall alone. This plant doesn't tolerate over-watering well. The only time you'll need to water a mature specimen is if there has been a prolonged very hot spell and the soil is excessively dry. It is even used in xeriscape gardens with restricted water.
Temperature and Humidity
Spur valerian does not like overly hot and humid summers which is why it won't grow in tropical conditions.
As you would expect with a plant that copes well in infertile soils, you won't need to fertilize your spur valerian.
Spur Valerian Varieties
Centranthus ruber's varieties come in a few other compatible colors:
- Centranthus ruber 'Coccineus' offers clusters of crimson blooms.
- Centranthus ruber 'Roseus' blooms in pink.
- Centranthus ruber 'Albus' offers white flowers on blue-green foliage.
Spur valerian dies to the ground in the winter and bounces back with the appearance of daughter plants around each base in the spring. It self-seeds readily, and cutting it back drastically after the bloom period can help to control any unwanted spread. It also means the bloom will be more abundant the following year. Spur valerian often blooms from early summer to September, so don't be tempted to cut back the flowers too early.
Propagating Spur Valerian
Basal cuttings can be taken in the spring or early summer, or you can divide the roots in spring or fall to produce new plants. Division every few years is recommended as this prevents the central section of clumps from dying off, and it stops the root system from becoming overcrowded.
How to Grow Spur Valerian From Seed
Growing spur valerian from seed produces good results. If you plan to sow during the winter, pick a sheltered spot, keep the soil slightly moist, and use a tray that can be covered to protect the seeds from any hard frost.
The seedlings can be transplanted into the ground when the temperatures rise, usually around May. Spur valerian seeds germinate rapidly when temperatures climb above 68 degrees Fahrenheit.
Sowing directly into the ground in spring is also possible. As the first leaves appear, it's a good idea to thin them out, selecting the most vigorous seedlings to keep. Make sure you water the seedlings regularly, but only enough to keep the soil mildly moist. Too much watering makes the plants look weedy.