Common Names: Cathedral Bells, Cup and Saucer Vine. Family: Polemoniaceae. Life Cycle: Half hardy perennial usually grown as a half hardy annual by gardeners. Height: 48 to 240 inches (120 to 600 cm). Native: Central America.
Growing Region: Zones 1 to 10. As a perennial in zones 9 and 10. Flowers: Summer and autumn, and through the winter in warm frost free areas. Flower Details: Purple, yellow, white, cream. Hanging bell or trumpet shape. Foliage: Alternate lobed leaves. Veined.
Sow Outside: Only in warm areas: Cover seed. Following last frost or autumn. Spacing 20 to 40 inches (50 to 100 cm). Sow Inside: Use Peat pots. Nick seeds. Lay pots on their sides to prevent rot. Germination time: one to seven weeks. Temperature 70°F (21°C). Eight weeks in advance. Transplant outdoors three weeks after the last frost; the temperature must not drop below 41°F (5°C).
Requirements: Full sunlight or partial shade. Average soil. Add manure to soil. Occasional feed. Pinch tips. Trellis. Regular watering. If growing perennial cut back/prune in spring. Propagate from stem cuttings.
How to Grow Cathedral Bells and other Cobaea
If planning to grow Cobaea from seeds indoors then the seeds should be nicked with a knife and sown in peat pots then covered lightly wit topsoil.
Cathedral bells take around two to four weeks to germinate and should be grown at about 22 to 24 degrees centigrade.
Cobaea should be started about two months before the seedlings are due to be transplanted in the middle of spring after the last possible frost. Seedlings should be spaced at about one meter into a sunny part of the garden.
Caring for Cobaea
Once growing the tips of Cobaea should be pinched to create branching.
Cobaea should be watered regularly and supported on a trellis.
I hope that you enjoyed this guide on how to grow Cobaea plants. You may also enjoy the following Gardener's HQ Polemoniaceae growing guides: How to grow Annual Phlox and Gilia plants.