Advice please on perennials for a north-facing wall along path
Whilst we have bluebells flowering along the path edge in the spring, we are looking for suggestions a long-flowering, relatively low-level plant that would bloom summer-autumn in the 20cm wide, narrow strip of soil along this north-facing wall. In early summer it gets sun first thing and then later from about 4:30pm through to sunset, but September-April onwards it is in full shade. Not wishing to have stems which fall over the path, nor just multi-coloured leaves instead of flowers. Location is Prestwick, South Ayrshire. Any suggestions would be very welcome.