1 litre sized pot.  An eye catching spider-like flower helps make this a feature in the garden.  It forms a trailing clump, dead-heading and regular trimming will help it maintain a better shape - one I had sprawled up an iceberg rose, the flowers looked good together but the osteospermum got straggly looking, would have benefited with better trimming!  The plants tolerate the light frost we get here and like a sunny position in well-drained soil.