This is a familiar sight in early summer growing wild in shady places in Britain. Its tall spires of drooping rose purple flowers will grace any garden in sun of part shade.
Sow in late spring early summer outdoors in a well prepared seed bed, very thinly, 1.5mm deep in drills 30cm apart, keep the soil damp until germination takes place and thin out the seedlings to 15cm apart when large enough to handle. Transplant 6cm apart into flowering site in the autumn for flowering the following year. They will grow in most soils and prefer part shade.