Passiflora QUADRANGULARIS

Passiflora QUADRANGULARIS - Giant Granadilla, Square-stalked Passion Flower, Passiflora quadrangularis, Barbadine.

Passiflora is a genus of vine-like plants in the passionflower family (Passifloraceae), native to tropical and subtropical climates of Australia, Asia, the Americas - particularly Peru and Brazil - the Mediterranean region, and with one species in Madagascar. The genus comprises around 500 species of visually distinct plants. There are annual and perennial varieties growing as herbaceous plants or evergreen climbing shrub-lianas, with dissected pinnate or simple fleshy dark-green leaves up to 10 cm (4 in) long that can change shape as they mature. In most species, specifically positioned glands on petioles and leaves secrete nectar that in nature serves to attract ants, which protect the plant from caterpillars. Simple unbranched tendrils emerge from the leaf axils, reaching toward support on their own. The plant stems lignify as they grow.

Each species blooms with beautiful solitary axillary fragrant star-shaped flowers on long pedicels. Large flowers up to 10-12 cm (4-5 in) in diameter consist of five petals and five sepals with large bracts framing an ovary with three stigmas surrounded by five stamens with fairly prominent anthers. Between the stamens and perianths are brightly colored filaments forming a violet-blue corona. Less common are varieties with red, white, purple, pink, and green flowers. Flowering can be observed from July to October. In the American tropics, flowers are pollinated by hummingbirds; under other conditions, this process is carried out by hand. After flowering, passionflower forms berry-like fruits up to 6 cm (2.4 in) long containing black seeds. The edible, tart-tasting, fragrant fruits of passion fruit and granadilla are widely known. Unripe fruits of all Passiflora species contain cyanides.

Giant granadilla is an evergreen woody liana producing very large, oval, edible fruits with a thick yellow rind and sweet-and-sour pulp up to 30 cm (12 in) long. This species is distinguished by the bright green coloration of its oval leaves and huge flowers up to 15 cm (6 in) in diameter.

Seeds are pre-scarified (lightly rubbed with sandpaper), soaked in hot water for 24 hours, and sown in a prepared mix of equal parts sod soil, peat, humus, and sand without deep burying. They are moistened with a spray bottle, covered with glass or film, and germinated in light at 22-25 °C (72-77 °F). Seedlings require ventilation. Avoid overwatering and desiccation of the sowings. Seeds germinate in 2 weeks to 6 months, occasionally up to 9 months. The cover is removed after germination. Seedlings are pricked out into individual pots after a pair of true leaves appears.

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Passiflora is very popular among flower growers due to its lack of fussiness and rapid growth. It prefers bright lighting; however, during midday summer hours it is better to shade the plant from direct sunlight to avoid scorching. On south-facing windows it displays maximum flowering; it grows excellently on western and eastern windows; on north windowsills and in light shade, it grows but blooms very sparsely. It can be moved outdoors into fresh air during the warm season. In winter, supplemental lighting with lamps is desirable. It requires a constant supply of fresh air, but does not tolerate drafts. In summer, the comfortable temperature is 20-25 °C (68-77 °F); in heat exceeding 30 °C (86 °F), the plant quickly loses ornamental appeal, turns yellow, dries out, and blooms very poorly. In winter during dormancy, it requires a cool rest at 10-15 °C (50-59 °F); without providing such conditions, it may drop leaves and even die.

Watering should be systematic and abundant from early spring to late autumn. The soil should always be kept moist; there is no need to wait for it to dry out, nor should water be allowed to stagnate in the saucer. In winter, watering is reduced to 3-4 times per month. In summer, it needs daily misting with soft water. It is important that direct sunlight does not hit the plant during misting to avoid scorching, so the procedure is best performed in the evening. A gentle warm shower can also be given every 7-10 days, taking care not to damage the fragile stems. Under insufficient air humidity, red spider mites may appear and flower buds may drop.

During the spring-summer period of vigorous growth, passionflower is fertilized every two weeks, alternating between organic and mineral fertilizers for indoor flowering plants at half dosage. The optimal element ratio in the fertilizer is: 4 parts potassium, 2 parts nitrogen, and 1 part phosphorus. The soil must be moistened before fertilizing. Foliar feeding once every 1.5 months is also recommended. In winter and under conditions unfamiliar to the plant, fertilizer should not be applied.

Repotting of young plants is carried out each year in spring, and of mature specimens once every 2-3 years. It is recommended to increase container size only slightly, because the more room the roots are given, the longer and bushier the vine will grow, but flowering will be poorer. A potting mix of equal parts sod soil, leaf mold, peat moss, and sand is used. It is best to pot on the plant into the new container without disturbing the soil ball. Pruning is carried out during repotting, watering is decreased, and misting is suspended.

Shoots require sturdy support and timely training in growth direction, as they grow quickly and lignify just as fast. In the first year, passionflower builds up its main stems, establishing the foundation of the future vine. Flowers appear only on young shoots; therefore, starting from 3 years of age, an annual spring pruning of basal shoots and 1/3 of secondary branches remaining from the previous year that have become bare is recommended. After flowering and fruiting, main branches are shortened by 3/4 of their length, and bare secondary shoots are pruned away completely. It is important not to prune flush with the main stem; leaving 4-5 cm (1.6-2 in) of shoot stub is necessary. Pruning should be carried out gradually in several stages; this prevents the die-off of large numbers of fine roots, sparing the plant from root rot and potential loss.