Onopordum: Scotch thistle, cotton thistle
Height 1.8m (6ft)
Planting distance 75cm (30in)
Flowers mid to late summer
Rich or ordinary garden
Sunny or partially shaded site
Scotch thistle (Onopordum acanthium) makes an excellent specimen plant in a border, large shrubbery or wild garden. It is grown for its dramatic foliage — broad silver-grey spiny leaves covered with white cobweb-like hairs – though purple thistle-likedo appear from mid to late summer.
Sow the seeds directly in the flowering site and thin to 75cm (30in) apart. If the plants are to reach their maximum size (1.8m/6ft tall), they should be grown in rich soil. However, ordinary garden soil in full sun or partial shade still gives good results. Remove dead flowers to prevent self-seeding.
Pests and diseases