Barleria is a genus of flowering plants and shrubs found in Africa and Southeast Asia. These plants have been exported to a number of other regions of the world and are invasive in some areas. Gardeners interested in cultivating members of this genus can often obtain seedlings at nurseries and through catalogs. These plants can also be easily propagated from seeds and cuttings, an option for people willing to engage in trades and exchanges with other gardeners.
Members of this genus are highly variable in appearance. They produce flowers in a range of colors including white, pink, and violet. The flowers commonly are somewhat tubular in appearance, and the foliage is glossy green, with simple broad leaves. Depending on the species, Barleria can have a shrubby or creeping growth habit, and some species can be seen clinging to trees and rocks in the forest understory.
These herbaceous plants prefer sun to part shade and require rich, well-drained soil. Compost can be a good soil amendment to promote healthy growth in new seedlings. Hardiness varies, depending on individual species. Some species can handle light frosts, while others require warm climates without extreme cold in the winter months. Some popular species for gardeners include bush violets, porcupine flowers, and the crested Philippine violet.
Barleria species can propagate in a number of ways. Many have branches that will root when they come into contact with bare soil, allowing the plant to spread quickly. All produce seeds and will readily self seed unless gardeners deadhead their plants to remove flowers before they start going to seed. Cuttings from hard or soft wood can also be used for propagation. The enthusiastic growth habits of these plants can become a problem in areas where vulnerable native species are present, as the Barleria can quickly crowd out native plants.
Gardeners can reduce the risks that Barleria will become invasive in the garden by controlling their growth with pruning and deadheading, in addition to growing them in containers or in isolated areas where it is easier to control the spread of the plant. Edging a planting with paving stones or gravel, for example, can help keep it contained. If a gardener is facing an invasion of unwanted plants, they need to be dug up, and it is advisable to sift the soil for root balls. Covering the area with a weed barrier for several months will prevent new growth, allowing the gardener to start again with new plants.