Nepeta govaniana

This is a little-known member of the catmint family but instead of the blue sort, which drives cats into a frenzy, this species plumps for something altogether more elegant and upright. The lemon yellow flowers at a metre high will need some gentle staking but continue to bloom all through summer and beyond. This is a good plant to combine with flowering grasses and the gentle blue of summer lavenders. (Ravenhill Nursery)