Passiflora caerulea aka Common Passion Flower

Passiflora caerulea, or blue passionflower, belongs to the passion vine family. This fast-growing vine comes from South America. Its range includes Bolivia, Brazil, Argentina, Paraguay and Uruguay. It grows along forest edges and in disturbed ground. It keeps its leaves where winters stay mild. In cooler places, it sheds them. Frost may kill the shoots, but roots can send up new growth.

Garden height varies from 10 to 40 feet [3–12 metres]. The RHS gives a narrower range of 26–39 feet [8–12 metres]. Width ranges from 3–6 feet [0.9–1.8 metres] at NC State. The RHS lists 8–13 feet [2.5–4 metres]. Smooth stems turn from green to brown. Coiled tendrils help the vine hold onto a support. Glossy green leaves grow in an alternate pattern. Most have five lobes, though some have three, seven or nine. Root suckers can spread and form dense patches.

Flowers open from early summer into early fall. Each grows alone on a long stalk and may have scent. Flowers span about 0.21–0.33 feet [0.064–0.10 metres]. White or pale pink tepals surround blue, white and purple filaments. Bees visit the blooms, which also draw butterflies. Green, egg-shaped fruits turn yellow or orange from late summer into fall. Their partly hollow centres hold many seeds and little red pulp. The ripe fruit is edible, but its taste is mild. People eat it raw, cook it, or make drinks. Flowers can also supply syrup.

Give this vine sun or partial shade and shelter. It grows in moist soil that drains well. Clay, loam and sand can all suit it. It accepts a wide range of soil pH. The RHS also lists drought resistance. Hardiness reports differ: Missouri Botanical Garden gives USDA zones 7–9. NC State lists zones 6–10, while the RHS rates it H4. In cold areas, grow it in a pot. Move it into a greenhouse or conservatory for winter.

Use it on fences, arbors, walls or trellises. It can also make a leafy screen. Growers use it in breeding and as rootstock for less hardy passionflowers. Its strong growth can become hard to control. Butterfly caterpillars may strip leaves from healthy plants. Under glass, watch for mites, whiteflies, mealybugs and scale. Poor airflow can favour fungal disease. Honey fungus and viruses are other risks. NC State warns that leaves contain cyanogenic glycosides. Eating them can cause nausea, vomiting, drowsiness and an uneven heartbeat. This warning matters despite other sources reporting no known hazards.