Tumbling over a stone wall not far from our home in Northamptonshire, the four main colours of red valerian, Centranthus ruber, are in full and glorious flower.

This lover of sunshine, dry walls and limey soil is prolific and a wonderful plant for bees, flowering for many weeks and self seeding generously. In fact the seedlings can be a pest and, when you try to pull them out, they have the irritating habit of snapping off leaving the root behind to shoot again.

The deep red, the white and two rosy red shades often grow together like this, or in various combinations, and as the plants self sow the balance of colours changes from year to year. Clouds of blue catmint or lavender make delightful companions.