Gardening in southern Spain: Collinsia heterophylla

Collinsia heterophylla, commonly called purple Chinese houses, innocence and blue-eyed Marys, are native to California, Baja California, Illinois and Kentucky. They have been introduced to many other parts of the world including Europe.

Although not drought hardy, these dainty annuals add a splash of bright colour to a Mediterranean garden and they can also be grown under trees and in containers.

At around 30cm tall, the spikes of flowers are formed by ever-decreasing-sized whorls of blooms, making them look like pagodas. The flowers, whose pollen and nectar attract bees, butterflies and other pollinating insects, come in soft tones of purple, lavender and blue, usually with a white upper lip. There are also completely white forms.

They need a rich, loamy soil with good drainage, regular watering and a location which gets shade especially on hot summer afternoons, and they will flower from spring until autumn. Deadheading will prolong the season even longer. After the flowers are over, capsules form containing around 20 seeds each. These open when dry and will keep the Chinese houses coming back every year.

The bright-green, lance-shaped leaves and other parts of the plant were traditionally used as an astringent to bring down inflammation and as an expectorant for mucous coughs.