Commelina coelestis

Commelina coelestis is a perennial tuberous plant that bears bright sky-blue flowers with yellow stamens all summer long. The flowers do not last long, but constantly renew themselves. Its flowers and foliage resemble those of its cousin, Tradescantia. It requires full sun and perfectly drained soil. It is not hardy so needs to be stored away in winter in cold climates.

It is originally from Central America and South America. It belongs to the Commelinaceae family. It forms a tuberous stump that develops delicate, semi-erect stems, forming an herbaceous clump 90cm (35in) tall. The flowering takes place from June to August, sometimes until September. The flowers consist of three petals, two of which are more developed, measuring 25mm (1in) in diameter. They form a bright contrast of colours in a sky-blue of rare intensity, highlighted by yellow stamens. They open in the morning and close in the afternoon. They constantly renew themselves, so that the plant always appears to be in bloom. The bright green and lanceolate leaves develop at the nodes located on fleshy and villous stems that they envelop. The tuber is formed by 3 to 6 "legs" that come together at a point from which the floral stem starts.

The tubers of Commelina coelestis are hardy in very well-drained, stony soil, and the flowers easily self-sow. Their magnificent blue blooms offer a rare and beautiful colour in the garden. They can be planted in the ground in mild climates. They will need winter protection in the form of mulch covered with a tarp to keep the fragile bulb dry. They will look wonderful in a rock garden with California poppies and Coreopsis 'Moonbeam'. This plant is also fabulous in a pot.