Cantua plants (Cantua buxifolia) are showy flowering shrubs with brightly colored, slender, tubular flowers that hang vertically from the bush. These distinctive plants are rare in cultivation and are native to the Andes, according to information published by the University of Connecticut. Also known as the Sacred Flower of the Incas, this attractive plant can grow as large as 7 feet tall and wide if given proper care. Cantua plants are best grown in United States Department of Agriculture (USDA) hardiness zones 8 and 9.
Plant your cantua in a location where it will receive at least a half-day's worth of sunlight, which is the minimum needed in order for this plant to thrive, according to information published by the Western Horticultural Society. Full sun or morning sun followed by afternoon shade is best for these spring-blooming shrubs.
Provide loose, loamy soil rich in organic matter. The soil should be well-draining to avoid the development of root rot. Amend poor soil with peat moss and leaf mold to improve draining and add nutrients, if necessary.
Water the plant when the soil begins to dry out. Cantuas need watering on average about once a week, according to the Western Horticultural Society, but this can vary with the climate. Do not over-water.
Prune immediately after the flowers have faded, as this plant blooms on the previous year's growth, recommends the University of Connecticut.
Mulch well in the spring to retain moisture in the soil and add nutrients. The use of an organic mulch is suggested by an article published by gardening.eu