These are tap rooted perennials discovered originally in Yunnan in China which have basal rosettes of 12in long leaves each of which is divided into six to ten pairs of leaflets with a larger leaflet at the end. The flowers are supported on long 12-20in stems and racemes of up to 10 tubular trumpet shaped flowers which are deep rose-pink to purple in June or July. I. delavayi ‘Snowtop’ has white flowers with a yellow throat.
Incarvillea delavayi are excellent plants for the herbaceous border or for mixed borders where they look best when grown in clumps of three or five plants for maximum effect. If you are planting dry roots or crowns rather than pot grown plants they need to be inserted 3-4in deep into the ground. Slugs can be a problem with the new growth in late spring but they readily grow through the problem. I. delavayi do best in full sun in well-drained soil and appreciate an autumn mulch.
Clumps can be divided in early spring taking care not to damage the main tap roots. Alternatively basal root cuttings can be taken from the dormant clump and brought into new growth in the greenhouse.