Cobaea scandens aka Cup And Saucer Vine

Cobaea scandens is a tender perennial vine in the phlox family. Gardeners call it cup and saucer vine or cathedral bells. Kew lists its native range as Mexico. Other garden sources extend that range into tropical South America. It climbs by tendrils and grows fast in warm weather. In cold regions, gardeners grow it as an annual. It keeps its leaves where conditions let it survive winter.

As an annual, it reaches 10–20 feet [3–6.1 metres] tall. Its spread is about 3–6 feet [0.9–1.8 metres]. RHS gives a smaller height range of 8–13 feet [2.5–4 metres]. In its frost-free home, it can reach 30–40 feet [9–12 metres]. The dark green, pinnate leaves have four leaflets. Each leaflet is about 0.33 feet [0.1 metres] long. Its quick growth needs a strong frame to climb.

Flowers hang down and open from late summer into fall. Each bell sits within a broad green calyx. This gives the bloom its cup-and-saucer shape. The flowers start green or greenish white, then turn purple. Each bloom lasts about four days. The petals join to form the bell. Newly opened flowers have a musky scent that some find unpleasant. Bats pollinate the flowers in the plant’s native habitat. The vine also draws bees, butterflies, and hummingbirds. Its fruit forms capsules that split open to shed seeds.

Give this vine full sun and shelter from harsh exposure. Some afternoon shade helps in places with hot summers. It grows in clay, loam, sand, or chalk. Soil should stay moist but drain well. RHS lists tolerance of acid, neutral, and alkaline soils. Water needs are moderate. Too much fertilizer can favor leaves at the expense of flowers. It survives winters in USDA zones 9–11. Its RHS rating is H2, so it does not withstand freezing. Start seeds indoors eight to ten weeks before the last frost. Softwood cuttings offer another way to raise plants.

Use this vine to cover fences, trellises, arbors, or walls. It also grows in large containers with firm support. Serious pest and disease issues are uncommon. Aphids and spider mites may still appear. Good airflow helps limit mildew in damp conditions. Sources differ on pruning time, suggesting late winter or after flowering. The supplied evidence does not establish edible uses or toxicity.