The unique and beautifully complex red passionflower is a favorite of tropical gardeners and tropical butterflies. Photograph by Adam Golatofski.
Description Passiflora racemosa is a strikingly beautiful evergreen vine with hanging, 1 ft (0.3 m) long clusters of 8-12 elaborately formed bright red flowers. The individual flowers are bowl-shaped, about 5 in (12.7 cm) across, and have ten bright red sepals and petals, collectively called "tepals." There are five purple and white structures called "coronas" perched above the tepals. The flowers usually are borne in opposing pairs on the pendent racemes, and are produced throughout the summer and fall. They yield to small, oblong, deep green edible fruits about 3 in (7.6 cm) in length. The stems of red passionflower are slender and angled, and the leaves are rather sparsely distributed. The 4 in (10.2 cm) leaves are glossy and leathery, and may be entire or three-lobed. Red passionflower grows to a length of 10-30 ft (3.1-9.1 m).
Red passionflower is indigenous to the state of Rio de Janeiro in Brazil.
Red passionflower does best with a well drained soil made from equal parts sand or gravel, peat, and loam. Passionflowers thrive on regular feeding with fertilizers high in potash. Care should be taken not to overwater or overfeed. Pests and diseases associated with growing Passiflora racemosa include spider mites, whiteflies, scale insects, leafspots, virus diseases and iron deficiency.
Light: Red passionflower needs full sun or partial shade and should be protected from drying winds and the hottest midday sun. Moisture: Red passionflower prefers a humid atmosphere and regular watering. The roots will rot if the soil is not well drained. Hardiness: USDA Zones 10 - 12. Red passionflower tolerates temperatures down to 50ºF (10ºC) for short periods. Propagation: Red passionflower is easily rooted from tip cuttings taken in spring or summer. Cuttings should include a node or small section (heel) of older wood. Passionflowers also can be grown from seed, although this method is more difficult; seeds should be soaked prior to planting and germination will be slow.
Usage Passiflora racemosa can be grown in a container. It is especially well suited for growing in the greenhouse or conservatory. It also can be grown as a house plant, but it needs high humidity. In frost free climates red passionflower is grown as a cover for a trellis, arbor, fence or garden teepee. Red passionflower can be planted next to an open shrub or tree and allowed to grow up through the branches. This is a vigorous plant and when mature it is likely to become tangled with dead growth in the center and should be pruned annually.
There are more than 500 species of passionflowers, and they are the exclusive larval food plants for more than 70 species of tropical and subtropical butterflies.
The name, Passiflora or "passion flower", was given by 16th century Spanish missionaries in South America who thought they saw a reference to the Crucifixion of Christ in the elaborate flower structures: The corona, sitting at the top of the flower, is the crown of thorns; the five anthers are the five wounds; the three styles are the three nails; and the five petals and five sepals are the apostles, less Judas and Peter.