Plant suggestions - does not spread

I have been given a tapered 44cm tall pot, 26cm inner diameter at top, to sit between our two south-facing garage doors. The pot is glazed, olivey-green (top), mottled mid- blue(bottom). The position gets plenty of light but no direct sunlight (except possibly in early summer mornings/evenings), and can get some south-westerly wind. Can you recommend a suitable plant that does not spread or can be trimmed to no wider than 29cm – something with blue flowers would be great!