What is Commelina?

Commelina is a genus of flowering plants known as dayflowers for their short-lived blooms. There are less than 200 species in this genus and they can be found all over the world in a wide variety of habitats and settings. Some are cultivated as ornamental plants, although gardeners should be advised that some ornamental species are also considered invasive and may not be a good choice for a low maintenance garden or a garden in a region with vulnerable native plants.

Members of this genus produce alternate leaves on lengthy, trailing to erect stems, depending on the species. Some will climb other plants or trellises, and they can also be grown in containers as trailing plants. The flowers are terminal, produced at the end of the stem, and have two large, showy petals with a third much smaller petal at the base of the bloom. Dayflowers come in colors like blue, purple, white, yellow, and apricot and several have been bred to produce colors in other ranges of the spectrum.

Commelina can grow as an annual or perennial, depending on the region. Some species produce rhizomes or tubers to store energy and propagate themselves. In regions like Asia, the leaves are eaten as leafy green vegetables; they can be sauteed, steamed, or boiled. The flowers of some species are edible as well. Also known as widow's tears, Commelina species are tolerant of a wide variety of conditions including cold climates and harsh soils.

Gardeners interested in cultivating ornamental species may be able to find them at nurseries or through trades with other gardeners. The soil should be well drained and medium to rich. Full sun to partial shade is recommended. If the plants are being grown as annuals, they can be removed once the foliage has died back in the fall. For perennials, pruning to shape the plant can be helpful for controlling growth and preventing the plant from becoming invasive.

Because some Commelina species can be invasive, gardeners should think carefully before planting them. It is advisable to establish them in an area of the garden with clear borders or boundaries, like paving stones or a stone wall, and to be aggressive about removing volunteer plants outside this area. If the plants become undesirable, they will need to be dug up and the soil should be sifted to remove any roots and starts. Laying down a weed barrier after clearing the Commelina plants out will help prevent new growth.