Common Valerian - Valeriana Officinalis
Valerian root is seductive to cats. Clusters of small sweetly-scented pale pink flowers appear in the summer. They have a vanilla scent. It is used as a herbal tea and is said to help insomnia and calm nerves. It grows well in shady damp environments.
Sow in early spring under cover, plant into individual pots when large enough to handle. They require some light to germinate.
NB. Not to be confused with RED VALERIAN (centranthus ruber) which despite its similar name is a completely different species.