Red Valerian a popular alien garden flower
RED VALERIAN is in full flower at present. Its flowers are big and showy and since it blooms profusely and has a long flowering period it is a plant that will continue to put on a great display until September. While it is found all over Ireland it is not native to our shores; rather, it is native to the Mediterranean and that being the case it grows best in full sun in places that are well drained and are free from hard frosts.
It is believed that the ' Valerian' part of its name almost certainly results from confusion between this alien plant ( Centranthus ruber) and our native Common Valerian ( Valeriana officinalis) from which herbalists of old extracted the sedative drug valeriana. 'Red' obviously refers to the colour of its longlasting flowers. However, while deep scarlet red is the common flower colour, there are forms that are both rose-pink and creamy off-white and these can be locally abundant. It is not unusual to see all three colour forms growing together.
The flowers are strongly scented but most people find their smell somewhat rank and unpleasant. Bees, butterflies and moths are strongly attracted to Red Valerian but slugs and snails are said to shun it. Migrant butterflies like Red Admirals and Painted Ladies that come to us from Mediterranean regions must find the plant a welcome sight when they arrive on our shores.
Red Valerian was a popular garden flower in the past. There is a record of it being cultivated in Britain in 1597. It was transported from its home range in south-west Europe and the Mediterranean to grace gardens in far flung places. It was brought to North America and Australia and everywhere in between. It seeded freely and where conditions permitted it escaped from the confines of gardens and established itself in the wild.
In naturalised itself in the wild in Ireland but it shunned wet places and shade. It also shuns acid places and rich soils. Consequently is most commonly to be seen on walls, disused quarries, sea cliffs, railway embankments, waste ground and other such places that are freely drained and are exposed to full sun. Lime mortar found on old walls is particularly attractive but since the roots can be quite woody damage to random rubble walls is likely to follow.
Red Valerian also thrives on the warm, limestone pavements in the Burren where it is regarded as an invasive weed.