Cup and saucer vine is a perennial climber native to subtropic regions of Mexico. It features thin, lightweight leaves and purple flowers that resemble the shape of a cup or bell, hence the unique name. This vine is a vigorous, rapid grower that can reach up to 30 or 40 feet in its natural environment. Seeds should be started indoors in the winter, then moved outdoors after the final frost has passed in spring. Although cup and saucer vine takes awhile to start blooming, its foliage will quickly make itself visible and create a screen or cover.
The plant has plentiful bright green leaves that are oblong in shape. The cup-shaped flowers are pale green as they start to open, but quickly turn purple or white as they fill out. The opening buds have a somewhat unpleasant scent, but once fully opened, the flowers develop a floral-honey fragrance.
|Botanical Name||Cobaea scandens|
|Common Names||Cup and saucer vine, cathedral bells|
|Plant Type||Perennial vine (typically grown as an annual)|
|Mature Size||10–20 ft. long, 3–6 ft. wide|
|Sun Exposure||Full sun|
|Soil Type||Moist but well-drained|
|Soil pH||Neutral to acidic|
|Bloom Time||Spring, summer|
|Flower Color||Green, maturing to purple|
|Hardiness Zones||9–11 (USDA)|
Cup and Saucer Vine Care
Cup and saucer vine grows so quickly that it's usually started from seed rather than from nursery plants. You can direct seed in the garden in spring after all danger of frost has passed, or get a head start on your seasonal garden by starting seeds indoors six to eight weeks before your last frost of the winter.
The blooms on the cup and saucer vines are pollinated mostly by bats when the plant is grown south of USDA hardiness zone seven. These flying mammals are generally harmless (and even helpful for controlling insects), but if the idea of bats flitting around your garden disturbs you, you may want to avoid this plant.
Start training the vines to grow up a structure or on a trellis early and they'll take it from there. To control the size of the plant, pinch off the stems when they reach the top of your support (or to your eye level)—this will encourage branching and bud set. Additionally, there is no need to deadhead the flowers. Keep in mind, this sprawling vine can easily engulf nearby plants. You can grow it in containers, but you'll need a large one, and it will need to be weighted to hold the weight of the vine and whatever support you include for it.
Cup and saucer vines need full sun to bloom well. If you live in an especially hot climate, your vines can probably stand a bit of afternoon shade, but you should still aim for at least six to eight hours of sunlight a day.
While your cup and saucer vine is not particular about soil pH or type, it does need a well-draining mixture to thrive. Additionally, mixing in some organic matter into your soil blend will keep your plant growing strong and blooming without the addition of fertilizer.
During the plant's growing season, it will need to be watered regularly—the soil should be allowed to drain but not dry out completely in between waterings. To master this balance, test the top few inches of soil with your finger—if it's dry, it's time to water. You can dramatically decrease your watering cadence to once a month or so during the winter months.
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 may die off in zone nine. If planting the 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.
Go easy on the fertilizer, or you will get a lot of vine growth and few flowers. If necessary, side-dress with compost in mid-summer for an extra boost of nutrition.
Grow Cup and Saucer Vine 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 to help speed up germination. Germination can be erratic, but you should see sprouts within two to four weeks. Since the vines will get entangled, you should start them in separate pots filled with ordinary potting mix. You may also find it helpful to insert a trellis immediately to keep them under control right from the start.
Common Pests and Diseases
Cup and saucer vine can attract aphids, especially when the plants are young and succulent. Frequent blasts of water or a couple of treatments of insecticidal soap should control them. Older plants can also fall prey to spider mites, especially during dry weather.