Cup-and-saucer vine (Cobaea scandens) is a climbing perennial plant that is native to Mexico. It produces large purple cup- or bell-shaped flowers that have inspired both of its common names: cup-and-saucer vine and “cathedral bells.” Because of its showy fragrant flowers, it is often cultivated as an ornamental plant and grown in gardens throughout the world.
I. Appearance and Characteristics
Cobaea scandens, the cup-and-saucer vine, cathedral bells, Mexican ivy, or monastery bells, is a species of flowering plant in the phlox family Polemoniaceae. It is native to Mexico, with isolated sightings elsewhere in tropical central and South America.
It is a self-clinging perennial climber. The Latin specific epithet scandens means ‘climbing’. The 4 in (10 cm) leaves comprise four leaflets and a tendril furnished with small hooks for clinging on to a support. The large forward-facing violet flowers, which are pollinated by bats in their native habitat, are bell-shaped with a pronounced ruff – hence the name cup-and-saucer. Mature flowers are scented. Present a capsule of fruits with seeds.
It is widely cultivated for its twining habit and its highly ornamental flowers, 5 cm (2 in) long, which change from white to purple. In temperate regions it is best grown as a half-hardy annual, sown in heat under glass in early spring, and planted out after all danger of frost is past. It has gained the Royal Horticultural Society’s Award of Garden Merit (confirmed 2017). A white form exists, C. scandens f. alba.
II. How to Grow and Care
Sunlight
Cup and saucer vines need full sun to bloom well. If you live in an especially hot climate, your vines can probably tolerate a bit of afternoon shade, but you should still aim for at least six to eight hours of sunlight each day.
Temperature and Humidity
As a summer annual, cup and saucer vine grows well in just about any growing zone. If grown as a perennial, it will be reliably hardy in USDA hardiness zones 10 and 11, but might die off in zone 9.
If direct-sowing seeds outdoors, be aware that young cup and saucer vine plants are sensitive to the cold, so give them some extra protection if the temperature dips below 50 degrees Fahrenheit.
Watering
Thriving in its native tropical rainforest habitat, cup-and-saucer vine has adapted to a consistent moisture environment and exhibits a preference for high humidity. This climber is moderately drought-tolerant but performs best when the soil remains evenly moist without becoming waterlogged. Watering should be done every week to maintain optimal hydration levels. As an evergreen plant, cup-and-saucer vine benefits from being grown outdoors where it can receive adequate rainfall, ensuring that its vigorous growth is supported by natural water cycles.
Soil
While your cup and saucer vine is not particular about soil pH or soil type, it does need a well-draining soil to thrive. Additionally, mixing in some organic matter into your soil will keep your plant growing strong and blooming without the addition of fertilizers.
Fertilizing
Fertilize cup-and-saucer vine bi-weekly during active growth with balanced, water-soluble fertilizers, diluting to half-strength to boost foliage and bloom vigor without overfeeding. Seasonal adjustments—less in winter, more in peak growing season—optimize fertilization. Apply strictly as directed, avoiding concentrated dosages that may damage cup-and-saucer vine’s roots. Use a gentle touch to maintain cup-and-saucer vine’s prolific flowering, ensuring each feed promotes its health and splendor.
Pruning
Deadhead blooms to encourage further flowering. Pruning is generally minimal but can be done to maintain shape and remove any dead or diseased growth. Late winter or early spring is the best time for any significant pruning.
Overwintering
In USDA Zones 9-11, the plant will generally survive the winter outdoors. In colder zones, consider growing it as an annual or bringing it inside during the cold months.
By following these guidelines, you can enjoy a healthy, vigorous Cobea scandens vine with eye-catching flowers from mid-summer through fall.
Propagation
A vigorous climber, cup-and-saucer vine thrives when propagated through sowing. For optimal growth, the seeds should be sown in well-drained soil mixed with compost to provide the necessary nutrients. A sunny spot with partial shade is ideal to support its early development. To encourage germination, a warm environment is beneficial. Once established, seedlings will need support to climb and can prosper indoors or outdoors, provided that they are protected from extreme weather. Regular watering and occasional pruning will help maintain vigor and a lush appearance.
How to Grow From Seed
Cup and saucer vine will readily self-seed, and the seedlings can be transplanted into other locations if you wish to spread your vines about. The seeds can also be collected for planting wherever you choose. They’re large, flat, and tough, so soaking them in water the night before planting helps accelerate germination. Germination can be erratic, but you should see sprouts within two to four weeks. Because the vines become entangled, you should start them in separate pots filled with ordinary potting mix. You might also find it helpful to insert a trellis immediately into the pots to keep the vines under control right from the start.
Transplanting
The ideal time to transplant cup-and-saucer vine is during S1-S2, also known as the perfect transplanting period, as it allows the plant ample time to establish roots before growth periods. Cup-and-saucer vine prefers a sunny to partly shaded site for optimum growth. When transplanting, ensure careful handling to prevent root damage.
Supporting
As a climbing plant, Cobea scandens requires a sturdy trellis, fence, or wall to climb. Ensure the support is in place at the time of planting to minimize disturbance later on.
Repotting
Repotting the vigorous climber cup-and-saucer vine every 2-3 years in spring to support its rapid growth. Choose a large, deep pot to accommodate the extensive root system. After repotting, ensure a sturdy support for its twining habits. Keep the soil moist for optimal recovery. This helps cup-and-saucer vine flourish, producing its unique, sizable flowers.
Pests and Diseases
Cup and saucer vine can attract aphids, especially when the plants are young and succulent. Frequent blasts of water or a few treatments of insecticidal soap should control them. Older plants can also fall prey to spider mites, especially during dry weather.
III. Uses and Benefits
- Ornamental uses
This vine is primarily used for ornamental purposes and is perfect for covering fences, walls, or pergolas. It also makes an attractive container plant when provided with a suitable structure to climb.
- Wildlife uses
The flowers attract a variety of pollinators, including bees and hummingbirds, making it an excellent addition to wildlife gardens.