1 litre sized pot.  Verbena officinalis var. grandiflora 'Bampton' is a stunning plant with its eye-catching purple tinted foliage and delicate pinky-purple flowers that cover it during summer.  Likes full sun in well-drained soil.  Reaching up to 90cm once established.  Dies back in winter to re-emerge come spring.  Loved by bees and beneficial insects.